I took an open jaw reward trip last year on AA from EWR-AUA, SXM-EWR. I was told that it was permitted so as long as both ends of the open jaw were in the same "zone." Because both places were in the Caribbean, which are in the same reward group, it was permitted. I was also going to CCS on that trip, but because South America is a different "zone" I could not have one end of the jaw there and another in the Caribbean. I had to purchase flights on ALM from AUA-CCS-SXM. Most airlines awards allow either an open jaw or a stopover, but not both.