diff --git a/src/main/java/tenor/AquireCraftingItems.java b/src/main/java/tenor/AquireCraftingItems.java
index 735b7170a..f461dfc01 100644
--- a/src/main/java/tenor/AquireCraftingItems.java
+++ b/src/main/java/tenor/AquireCraftingItems.java
@@ -17,8 +17,6 @@
 
 package tenor;
 
-import java.util.List;
-
 public class AquireCraftingItems extends QuantizedTaskNode implements IClaimProvider {
 
     final CraftingTask parent;
@@ -51,11 +49,11 @@ public class AquireCraftingItems extends QuantizedTaskNode implements IClaimProv
         return x -> {
             // cost to get x copies of these items
             double sum = 0;
-            for (QuantizedToQuantizedTaskRelationship resource : (List<QuantizedToQuantizedTaskRelationship>) (Object) childTasks()) {
+            for (IQuantizedParentTaskRelationship resource : childTasks()) {
                 int amountPerCraft = parent.inputSizeFor((AquireItemTask) resource.childTask());
                 int totalAmountNeeded = x * amountPerCraft;
 
-                int amountForUs = resource.quantityCompleted();
+                int amountForUs = ((IQuantizedChildTaskRelationship) resource).quantityCompleted();
                 totalAmountNeeded -= amountForUs;
 
                 if (totalAmountNeeded <= 0) {
@@ -75,8 +73,8 @@ public class AquireCraftingItems extends QuantizedTaskNode implements IClaimProv
         }
         // our only parent is the crafting task
         int minCompletion = Integer.MAX_VALUE;
-        for (IQuantizedChildTaskRelationship resource : (List<IQuantizedChildTaskRelationship>) (Object) childTasks()) {
-            int amountForUs = resource.quantityCompleted();
+        for (IQuantizedParentTaskRelationship resource : childTasks()) {
+            int amountForUs = ((IQuantizedChildTaskRelationship) resource).quantityCompleted();
 
             int amountPerCraft = parent.inputSizeFor((AquireItemTask) resource.childTask());
 
diff --git a/src/main/java/tenor/AquireItemTask.java b/src/main/java/tenor/AquireItemTask.java
index 47e659862..6d7c07457 100644
--- a/src/main/java/tenor/AquireItemTask.java
+++ b/src/main/java/tenor/AquireItemTask.java
@@ -21,7 +21,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
-public class AquireItemTask extends QuantizedTaskNode implements IClaimProvider, IQuantizedDependentCostCalculator<IQuantizedChildTaskRelationship> {
+public class AquireItemTask extends QuantizedTaskNode implements IClaimProvider, IQuantizedDependentCostCalculator<IQuantizedChildTaskRelationship, IQuantizedParentTaskRelationship> {
 
     HashMap<IQuantizedChildTaskRelationship, Integer> allocation; // allocation of what tasks have claim over what items in our inventory i guess
 
diff --git a/src/main/java/tenor/IChildTaskRelationship.java b/src/main/java/tenor/IChildTaskRelationship.java
new file mode 100644
index 000000000..4b1e50522
--- /dev/null
+++ b/src/main/java/tenor/IChildTaskRelationship.java
@@ -0,0 +1,21 @@
+/*
+ * This file is part of Baritone.
+ *
+ * Baritone is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Baritone is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Baritone.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package tenor;
+
+public interface IChildTaskRelationship {
+}
diff --git a/src/main/java/tenor/IParentTaskRelationship.java b/src/main/java/tenor/IParentTaskRelationship.java
new file mode 100644
index 000000000..e3cfc7ce1
--- /dev/null
+++ b/src/main/java/tenor/IParentTaskRelationship.java
@@ -0,0 +1,21 @@
+/*
+ * This file is part of Baritone.
+ *
+ * Baritone is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Baritone is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Baritone.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package tenor;
+
+public interface IParentTaskRelationship {
+}
diff --git a/src/main/java/tenor/IQuantizedChildTaskRelationship.java b/src/main/java/tenor/IQuantizedChildTaskRelationship.java
index 33775827b..ec46f80b8 100644
--- a/src/main/java/tenor/IQuantizedChildTaskRelationship.java
+++ b/src/main/java/tenor/IQuantizedChildTaskRelationship.java
@@ -17,7 +17,7 @@
 
 package tenor;
 
-public interface IQuantizedChildTaskRelationship<T extends ITaskNodeBase> extends ITaskRelationshipBase<T, IQuantizedTask> {
+public interface IQuantizedChildTaskRelationship<T extends ITaskNodeBase> extends ITaskRelationshipBase<T, IQuantizedTask>, IChildTaskRelationship {
 
     double allocatedPriority(int quantity);
 
diff --git a/src/main/java/tenor/IQuantizedDependentCostCalculator.java b/src/main/java/tenor/IQuantizedDependentCostCalculator.java
index 6e0fccf97..9f4d8d4e5 100644
--- a/src/main/java/tenor/IQuantizedDependentCostCalculator.java
+++ b/src/main/java/tenor/IQuantizedDependentCostCalculator.java
@@ -17,23 +17,23 @@
 
 package tenor;
 
-public interface IQuantizedDependentCostCalculator<T extends ITaskRelationshipBase> extends ITaskNodeBase<T> {
+public interface IQuantizedDependentCostCalculator extends IQuantizedTaskNode {
     default IQuantityRelationship cost() {
         switch (type()) {
             case SERIAL:
             case PARALLEL_ALL:
                 return q -> {
                     double sum = 0;
-                    for (ITaskRelationshipBase relationship : childTasks()) {
-                        sum += ((IQuantizedParentTaskRelationship) relationship).cost().value(q);
+                    for (IQuantizedParentTaskRelationship relationship : childTasks()) {
+                        sum += relationship.cost().value(q);
                     }
                     return sum;
                 };
             case ANY_ONE_OF: // TODO this could be smarter about allocating
                 return q -> {
                     double min = -1;
-                    for (ITaskRelationshipBase relationship : childTasks()) {
-                        double cost = ((IQuantizedParentTaskRelationship) relationship).cost().value(q);
+                    for (IQuantizedParentTaskRelationship relationship : childTasks()) {
+                        double cost = relationship.cost().value(q);
                         if (min == -1 || cost < min) {
                             min = cost;
                         }
diff --git a/src/main/java/tenor/IQuantizedParentTaskRelationship.java b/src/main/java/tenor/IQuantizedParentTaskRelationship.java
index cd60024cd..3689429e7 100644
--- a/src/main/java/tenor/IQuantizedParentTaskRelationship.java
+++ b/src/main/java/tenor/IQuantizedParentTaskRelationship.java
@@ -17,7 +17,7 @@
 
 package tenor;
 
-public interface IQuantizedParentTaskRelationship<T extends ITask> extends ITaskRelationshipBase<QuantizedTaskNode, T> {
+public interface IQuantizedParentTaskRelationship<T extends ITask> extends ITaskRelationshipBase<QuantizedTaskNode, T>, IParentTaskRelationship {
 
     IQuantityRelationship cost();
 }
diff --git a/src/main/java/tenor/IQuantizedTaskNode.java b/src/main/java/tenor/IQuantizedTaskNode.java
index 79e099c58..080e684a5 100644
--- a/src/main/java/tenor/IQuantizedTaskNode.java
+++ b/src/main/java/tenor/IQuantizedTaskNode.java
@@ -21,6 +21,6 @@ package tenor;
  * @author Brady
  * @since 10/30/2018
  */
-public interface IQuantizedTaskNode extends ITaskNodeBase<IQuantizedChildTaskRelationship>, IQuantizedTask {
+public interface IQuantizedTaskNode extends ITaskNodeBase<IQuantizedChildTaskRelationship, IQuantizedParentTaskRelationship>, IQuantizedTask {
 
 }
diff --git a/src/main/java/tenor/ISingularChildTaskRelationship.java b/src/main/java/tenor/ISingularChildTaskRelationship.java
index 78b94dec0..d6dfaa69f 100644
--- a/src/main/java/tenor/ISingularChildTaskRelationship.java
+++ b/src/main/java/tenor/ISingularChildTaskRelationship.java
@@ -17,7 +17,7 @@
 
 package tenor;
 
-public interface ISingularChildTaskRelationship<T extends ITaskNodeBase> extends ITaskRelationshipBase<T, ISingularTask> {
+public interface ISingularChildTaskRelationship<T extends ITaskNodeBase> extends ITaskRelationshipBase<T, ISingularTask>, IChildTaskRelationship {
 
     double allocatedPriority();
 }
diff --git a/src/main/java/tenor/ISingularParentTaskRelationship.java b/src/main/java/tenor/ISingularParentTaskRelationship.java
index c3f7c92fe..74101869a 100644
--- a/src/main/java/tenor/ISingularParentTaskRelationship.java
+++ b/src/main/java/tenor/ISingularParentTaskRelationship.java
@@ -17,7 +17,7 @@
 
 package tenor;
 
-public interface ISingularParentTaskRelationship<T extends ITask> extends ITaskRelationshipBase<SingularTaskNode, T> {
+public interface ISingularParentTaskRelationship<T extends ITask> extends ITaskRelationshipBase<SingularTaskNode, T>, IParentTaskRelationship {
 
     double cost();
 }
diff --git a/src/main/java/tenor/ISingularTaskNode.java b/src/main/java/tenor/ISingularTaskNode.java
index eb2f41de5..74b4ffb28 100644
--- a/src/main/java/tenor/ISingularTaskNode.java
+++ b/src/main/java/tenor/ISingularTaskNode.java
@@ -21,6 +21,6 @@ package tenor;
  * @author Brady
  * @since 10/30/2018
  */
-public interface ISingularTaskNode extends ITaskNodeBase<ISingularChildTaskRelationship>, ISingularTask {
+public interface ISingularTaskNode extends ITaskNodeBase<ISingularChildTaskRelationship, ISingularParentTaskRelationship>, ISingularTask {
     double priorityAllocatedToChild(ISingularParentTaskRelationship relationship);
 }
diff --git a/src/main/java/tenor/ITask.java b/src/main/java/tenor/ITask.java
index eee9d1c85..231770b3e 100644
--- a/src/main/java/tenor/ITask.java
+++ b/src/main/java/tenor/ITask.java
@@ -19,7 +19,7 @@ package tenor;
 
 import java.util.List;
 
-public interface ITask<T extends ITaskRelationshipBase> {
+public interface ITask<T extends IChildTaskRelationship & ITaskRelationshipBase> {
 
     List<T> parentTasks();
 
diff --git a/src/main/java/tenor/ITaskNodeBase.java b/src/main/java/tenor/ITaskNodeBase.java
index 143e76f96..1268962e2 100644
--- a/src/main/java/tenor/ITaskNodeBase.java
+++ b/src/main/java/tenor/ITaskNodeBase.java
@@ -19,11 +19,11 @@ package tenor;
 
 import java.util.List;
 
-public interface ITaskNodeBase<T extends ITaskRelationshipBase> extends ITask<T> {
+public interface ITaskNodeBase<T extends IChildTaskRelationship & ITaskRelationshipBase, S extends IParentTaskRelationship & ITaskRelationshipBase> extends ITask<T> {
 
-    List<ITaskRelationshipBase> childTasks();
+    List<S> childTasks();
 
     DependencyType type();
 
-    void addChild(ITaskRelationshipBase relationship);
+    void addChild(S relationship);
 }
diff --git a/src/main/java/tenor/QuantizedTaskNode.java b/src/main/java/tenor/QuantizedTaskNode.java
index a0c659416..0c8768de0 100644
--- a/src/main/java/tenor/QuantizedTaskNode.java
+++ b/src/main/java/tenor/QuantizedTaskNode.java
@@ -17,7 +17,7 @@
 
 package tenor;
 
-public abstract class QuantizedTaskNode extends TaskNode<IQuantizedChildTaskRelationship> implements IQuantizedTask {
+public abstract class QuantizedTaskNode extends TaskNode<IQuantizedChildTaskRelationship, IQuantizedParentTaskRelationship> implements IQuantizedTask {
 
     public QuantizedTaskNode(DependencyType type) {
         super(type);
@@ -37,7 +37,7 @@ public abstract class QuantizedTaskNode extends TaskNode<IQuantizedChildTaskRela
         }
         int minQuantity = -1;
         for (int i = 0; i < childTasks().indexOf(child); i++) {
-            QuantizedToQuantizedTaskRelationship relationship = (QuantizedToQuantizedTaskRelationship) childTasks().get(i);
+            IQuantizedChildTaskRelationship relationship = (IQuantizedChildTaskRelationship) childTasks().get(i);
             IClaimProvider claim = (IClaimProvider) relationship.childTask();
             int amt = claim.quantityCompletedForParent(relationship);
             if (minQuantity == -1 || amt < minQuantity) {
diff --git a/src/main/java/tenor/SingularTaskNode.java b/src/main/java/tenor/SingularTaskNode.java
index ead3dffbc..51c30acf5 100644
--- a/src/main/java/tenor/SingularTaskNode.java
+++ b/src/main/java/tenor/SingularTaskNode.java
@@ -17,7 +17,7 @@
 
 package tenor;
 
-public abstract class SingularTaskNode extends TaskNode<ISingularChildTaskRelationship> implements ISingularTaskNode {
+public abstract class SingularTaskNode extends TaskNode<ISingularChildTaskRelationship, ISingularParentTaskRelationship> implements ISingularTaskNode {
 
     public SingularTaskNode(DependencyType type) {
         super(type);
diff --git a/src/main/java/tenor/Task.java b/src/main/java/tenor/Task.java
index 372ce8890..854257de3 100644
--- a/src/main/java/tenor/Task.java
+++ b/src/main/java/tenor/Task.java
@@ -19,7 +19,7 @@ package tenor;
 
 import java.util.List;
 
-public abstract class Task<T extends ITaskRelationshipBase> implements ITask<T> {
+public abstract class Task<T extends IChildTaskRelationship & ITaskRelationshipBase> implements ITask<T> {
 
     List<T> parentRelationships;
 
@@ -33,7 +33,7 @@ public abstract class Task<T extends ITaskRelationshipBase> implements ITask<T>
         if (relationship.childTask() != this) {
             throw new IllegalArgumentException();
         }
-        relationship.parentTask().addChild(relationship);
+        relationship.parentTask().addChild((IParentTaskRelationship) relationship);
         parentRelationships.add(relationship);
     }
 }
diff --git a/src/main/java/tenor/TaskLeaf.java b/src/main/java/tenor/TaskLeaf.java
index 7575124f3..c79c5a932 100644
--- a/src/main/java/tenor/TaskLeaf.java
+++ b/src/main/java/tenor/TaskLeaf.java
@@ -17,5 +17,5 @@
 
 package tenor;
 
-public abstract class TaskLeaf<T extends ITaskRelationshipBase> extends Task<T> {
+public abstract class TaskLeaf<T extends IChildTaskRelationship & ITaskRelationshipBase> extends Task<T> {
 }
diff --git a/src/main/java/tenor/TaskNode.java b/src/main/java/tenor/TaskNode.java
index aabe5d0fc..5e4467d61 100644
--- a/src/main/java/tenor/TaskNode.java
+++ b/src/main/java/tenor/TaskNode.java
@@ -19,24 +19,27 @@ package tenor;
 
 import java.util.List;
 
-public abstract class TaskNode<T extends ITaskRelationshipBase> extends Task<T> implements ITaskNodeBase<T> {
+public abstract class TaskNode<T extends IChildTaskRelationship & ITaskRelationshipBase, S extends IParentTaskRelationship & ITaskRelationshipBase> extends Task<T> implements ITaskNodeBase<T, S> {
 
-    List<ITaskRelationshipBase> childRelationships;
+    List<S> childRelationships;
     public final DependencyType type;
 
     public TaskNode(DependencyType type) {
         this.type = type;
     }
 
-    public List<ITaskRelationshipBase> childTasks() {
+    @Override
+    public List<S> childTasks() {
         return childRelationships;
     }
 
+    @Override
     public DependencyType type() {
         return type;
     }
 
-    public void addChild(ITaskRelationshipBase relationship) {
+    @Override
+    public void addChild(S relationship) {
         if (relationship.parentTask() != this) {
             throw new IllegalArgumentException();
         }