Plastic panel repair

[Doug1]

I need to fix these couple of spots in one of the back interior panels for a 2nd Gen F-body. I tried some expensive plastic repair but it didn't hold. Since both of these cracks are where the piece fits over the seam visible when you open the door, I need to use something thin but strong so the part will still fit over the seam.
I think I probably need to take some thin, pliable, strong plastic and glue it to the backside of these pieces. If I can get the pieces to stay together, I can fill in the cracks and re-texture them before dying them. What's the solution to getting plastic to stick to plastic?
https://static1.pt-content.com/images/pt/2016/11/IMG_2945_zpshmcqlxnh-1.jpg
https://static1.pt-content.com/images/pt/2016/11/IMG_2946_zpswskx43r7-1.jpg

[csouth]

What about plastic welding?

[Doug1]

Those were for a fully restored 2nd Gen. Tried welding but it looked like crap so I just used some newer panels. Not a fan of trying to fix old stuff. That's why I like pro-touring. :-)