Hey there! This is pretty complicated, so I will try to keep my explanation simple. Let me know if you need more clarification!
I have two master controls that I'm using to move a bunch of bones around (I'll attach a screenshot).
control_path is the parent and is constrained to a path. This is moving the head around on a smooth loop for our idle animations. It's moving from 0 > 100 on the path, so it loops indefinitely.
control_master is the child control and NOT constrained to a path. We are moving this around freely and keying it for our reaction animations. In this case, we want the parent control (what we're using for idles) to basically do nothing.
I set it up this way because we need both 1) a bone to move on a path 2) a bone to move freely.
The problem: We want to be able to interrupt an idle animation with a react. So wherever control_path is sitting at that point in time, we want it to leave that path and blend in a straight line to where the control_master is keyed for the reaction anim. It seems to me that when a bone is constrained, it is always constrained. Is there a way to detach it?
We've been trying this a few ways - both on the same track & reacts on a higher track and we're seeing a hard cut from one position to the other & no blending. We also need to blend other bones, so we are thinking that we'll need to use the same track.
Here's a video of how both controls work: https://drive.google.com/file/d/0B2E2rSrYAKvQTC1ZNV9uZlRDa1U/view?usp=sharing