Custom Unity Generic Avatar and Avatar Mask generation code

Hey, this project is very simple: I have a series of nested Unity Game objects generated by a C# unity package (called Spriter2Unity). Example: Root Chest Arm 1 Arm 2 Upper Leg Front Lower Leg Front Upper Leg Rear Lower Leg Rear I am using the animations generated by this UnityPackage to build an Animator state machine. It works great! Blends well, mixes well! However, I want to setup a Avatar Mask which can be used to blend in Additive animations against the nested game object. (I want to blend in animations from only a portion of the hierarchy.) The completion criteria for this task is as follows: 1) Ability to select a Game Object in a scene (with many branching children of non-humanoid shape) and click a button to Generate a Generic Avatar. 2) That Generic Avatar can be used to Generate an Avatar Mask. 3) The Avatar Mask can be used with Mechanim to blend in part of the animations using the Unity Layer system and the animations I provide.