Syncing different framerates - picture in picture

I'm a new user coming from Kino.  I'm trying to create a picture in picture effect using the composite transition, using two different cameras on the same subject.  The cameras have different frame rates, one is 29.97 (or whatever nonsensical rate that is supposed to be) and the other is 25fps.  When I do the transition, they go out of sync.

Has anyone else had trouble with this?  Are there any solutions that I can do within Kdenlive?  I suspect I may have to change the framerate of the 25fps clips to 29.97fps using ffmpeg or mencoder - any ideas how I can do this?