Rear window defogger on 97 Park Avenue is not working. Also, heated front seats not working. I think they are on the same circuit. Checked fuses and they seem to be okay. Would scratched lines in defogger cause the defogger and heated seats to not work?

I believe you have two seperate issues.

Yes, scratched lines in the defogger will stop the defogger from working. The lines are made from metalic paint and is part of the circuit. It acts as a mini heating coil. A volt meter can be used to find breaks. If you have a break, it can be repaired. Parts stores sell a defogger repair kit consisting of special metalic rich paint to bridge to gaps.