That is very cool. I just linked two reservations that only have the last two segments in common; one reservation is three segments and the other is four segments. But I got the "successfully linked" message, so apparently it worked.

I assume that the linked person will not be automatically upgraded with me as my MVPG companion. I'm in paid F and she is using my gold guest upgrade, but there is currently no U space for our last segment, so she's in coach; we'll see what happens.