Trevor, I have a 92 325i with the same problem!
a friend of mine with a 328 suggested I use a hypo filled with super glue
and inject it where needed. I guess you would have to hold each section
down until the glue adheres and go in little steps. I guess the worst that
happens is that we f--- it up and have to go for a different fix or a new
panel! Good luck! If you hear of any other ideas, let me know ok?