Following a blunder in which a camera position is in shot I made a dummy backdrop to composite this with the action clip and hide the camera. I have been using Animatte, which kind of works but I am finding it difficult to get the paths to stay put once I have set them out on a frame: they develop a life of their own and display nonsense tracks.
* how do I get Avid to remember my tracing and not modify them?
* is there a better and/or less time consuming option than Animatte?
I'm not sure why you would be having those issues with animatte. Are you simply pulling a fixed key or are you plotting a path between keyframes. If fixed is it possible you're setting a key frame on the timeline drawing your shape and moving it so it's animating between the keyframe that you've created and the start and end key frames?
In the key section of the BCC effects there's quite a few options for matte and key's that you might prefer to use.