well, after trying most of the suggestions in this thread, I have come up empty. Not successful in getting through to someone who can help at the hotel by phone and trying the email suggested by writerguyfl has not yielded an answer from the hotel (although Marriott customer care did forward what I wrote tothe hotel).
So I will cancel the Residence Inn reservation and book the Home2Suites by Hilton since they can guarantee three beds as a standard award. Besides, I wouldn't mind burning a few HH points since their devaluation has left me less enchanted with their program.