Unity - Scripting API:

public function CreateBlendTreeChild(threshold: float): Animations.BlendTree;

public Animations.BlendTree CreateBlendTreeChild(float threshold);

public function CreateBlendTreeChild(position: Vector2): Animations.BlendTree;

public Animations.BlendTree CreateBlendTreeChild(Vector2 position);

Parameters

position	The position of the child. When using 2D blend trees.
threshold	The threshold of the child. When using 1D blend trees.

Utility function to add a child blend tree to a blend tree.

The blend tree asset that is created is added as a sub asset of the blend tree. This function pushes an Undo operation.