Thinking off the top of my head, GSN has the rights (and the tapes) to the following Passwords:
1. Primetime CBS Episodes
2. Daytime CBS Episodes (1966-1967 ONLY)
3. Password Plus
4. Super Password
I imagine that if any more CBS daytime episodes were found, GSN would have those as well. As for the ABC destroyed episodes, I imagine that if they were found, GSN would get them as well as part of the MGP package. I believe they had one surviving episodes converted with the intent to air it, but the quality was too poor.