[rhizome]

IANAL, but you sound like you're in the catbird seat. They need all formers to sign this, they laid you off, you have side projects and a life, and so why devote a thought to their needs? Charity?

Turn it around and tell them your needs: you don't want to lose rights to your own work. Leave at that at first, and see if they come back with anything, such as a list of the specific works they want you to disclaim prior to their acquisition.

You get the open end, not them.

And charge them for laying you off, I assume you don't have equity that will act as any kind of redemption in the sale.