This really doesn't make any sense. I have 30-70 FP objects in a scene with hundreds of objects inside. Most are hidden due to render constraints. So what you are saying is that I have to assign object ID's to every single object to be able to make a matte element for a FP object?
Also I just realized that FP objects are not visible in the Alpha channel either. They simply do not render. So with FP7, FP objects are not considered "objects" anymore? You really need to have a look at this. Attached is a render with the alpha problem. How do I get the trees to be part of the Alpha channel?