Hi!
I don't mean to interfere with a role play game I'm not even going to take part in at this time. However, it may be an option to settle for a compromise. For any land before time character who doesn't appear in the movies one or two of the movie characters need to be taken care of by somebody who introduces an own character. It's just a suggestion, and I don't know if it works, but it would mean neither banning own characters, nor would it make it likely that the important LBT characters won't be taken care of.