Realize this thread is years old, but were you able to make this change without any difficulties or fees?

I'm in a similar situation...one itin, 5 pax, might want to switch dates for 1 person. All US/AA metal, AAdvantage award, AA ticket stock. Origin/destination unchanged.

Don't care about the status implications...the person "breaking off" will be nonelite and just have to deal with a lousy seat. Just the ability to do it without affecting the underlying 4 tickets that we do not want to change.