SDandi – if I’m understanding what you’re trying to achieve, it is:
- For your husband to have two Nth American trips as part of his DONE4
- One to New York, which will require 3 segments, because of the restriction of only one trans-continental flight allowed (you have SAN-JFK-TUS-SAN)
- And the other to somewhere in the Caribbean
Also:
- As Christep has pointed out, up to six flights are allowed in North America, and therefore your only have three available for the Caribbean trip.
- There are no direct Oneworld flights from SAN to any Caribbean or Central American destination
After all that, here’s my suggestion:
- New York: SAN-JFK-xxx-LAX; separate flight or train* to get home to SAN
- Caribbean: separate flight or train to LAX, then LAX-yyy-zzz-SAN
Possibilities for yyy are: BZE, MBJ, and a bunch of places in Mexico (CUN, MZT, MEX, PVR, SJD) – source “where we fly” on oneworld.com
* The train option is pretty good: last November I travelled by train from San Diego Old Town to LA Union Station for USD31.45 and then paid USD9 for the bus from Union Station to LAX