I have a 84 BMW 633 CSI that the dash is cracked and raised around the cracks. As well as the speaker pods / headrests in the rear. I havent had any luck locating a replacement so I need to try to repair what I have. The cracks are anywhere from 1/8 to 1/4 inch wide and 3 to 5 inches long in places. What, if anything, can I fill these with and sand down so I can retexture / cover them with?? Should I just remove whatever is the covering and start all over ?
I have read all the posts here about dash cracks and none have helped. Also need to have assistance in removing 15 year old tint from the rear window that has a defrost grid in it. I dont really need the defrost grid in texas but want to save it if possible. the stuff is flaking the the layer on the inside but the side towards the glass in very much still intact. have tried heat gun, ammonia & water...what is left. I am trying to restore / customize this car and need a lot of help with the "little stuff"

I have read on certain websites were people have used a kind of liquid plastic called Rigid Plastic repair. Apparently you can buy it in a local automotive store. I would recommend taking out the parts that have the cracks first, then filling in the cracks from both sides. After it dries hard (dont know how long it takes) you sand it smooth. Then I would clean the peice off real good with rubbing alcohol and repaint it so it looks nice and spiffy.