Well, it looks like you have had a lot of situations like this. I would say copyright everything you do. There are sharks out there! I have meet my share. If this is happening to you, I would learn from it and do everything right...
I remember when pac was on a dvd talking bout dre be buying songs/beats of people for 500 a cd.. then claiming there his, And alot of the old dre beats were done by daz, and jellyroll who did the still dre beat said the same thing. jayz said he wrote still dre