If I fly from West Coast to East Coast for Christmas, and then have a friend meet me somewhere else for NYE, lets say, Nassau Bahamas, or Puerto Vallarta, but it doesn't really matter, and then we fly home TOGETHER, what is the best way to do this so he can share in most of the benefits?

I would normally say duh, just book one ways, but there are a couple of complicating factors:

• International 1-ways are often more money, as opposed to domestic where it seems to be extremely rare for a need to book RT for saving $$$
• Perhaps my flight is GSP-CLT-NASSAU and his is LAX-CLT-NASSAU ... with the CLT-NASSAU being the same flight (cancellations or delays willing, of course) are the chances of getting the second leg PNRs for the first half of this trip merged about a big fat 0? For the return, our legs would be identical.