How do I add a crosshair guide to a FCPX angle editor viewer window? I need to keyframe the Y position transform of a moving subject to keep her in the center of the frame and would like a set of crosshairs to help me do it.  I've seen solutions which employ Motion titles, but I can't get this to work because the clip I'm translating is inside a multicam clip. I've looked, but cannot find, plugins to add this functionality. Thanks
It is indeed impossible to put a title over a clip inside a multi cam clip... Unless you turn that clip into a compound clip. Then you can add whatever overlay you want to it.

So you will have:


keyframed clip with crosshair overlay
inside a compound clip
inside a multicam clip


Just right click your the clip inside your multicam clip and choose New Compound Clip ( ⌥  + G )