Join Date: Dec 2008
Location: Mostly living in the basement
Programs: Free Agent Level 2; MR LT(!)TE, HH SE, ALL SE, BAC Silver, DL MM, UA PS, 2V Fanboi, CBP GE
Posts: 5,341
There is no ambiguity, your parents are "on a domestic flight connecting to/from a same day international Delta One Flight" and will have access at MCO.
Note at JFK they will have access to the Virgin Clubhouse and both SkyClubs.