Question:

If a particular jet comes equipped with three 4 man life rafts cant hey be replaced with a single 12 man raft or are they part number specific to the aircraft? Our Challenger has life raft PN:xxxxx but the manufacturer is out of business. Another manufacturer has a different part number to replace the originaly 3 rafts, but I'm interested in exploring replacing the original 3 life rafts with a single 12 person raft. Can this be done?

That is a question for your regulatory authority, not an internet forum.

Joe