Hi Carrie,
I didn't have a problem working with the offsite WC. I had Marisol and it did take her a few days to respond to me each time but I began my communications early and was able to get everything planned.
I would highly recommend visiting the resort and making sure you like it. We were not happy with the lack of service and meager portions. Onsite coordinator and hotel wedding coordinator weren't very helpful. The groomsmen took over executing the wedding and moving the timeline along so that everything was captured by the photographers/videographers before they left (we opted for half day package).
We had a dispute with the hotel that was not resolved. The hotel manager told us to contact customer service manager Ana Pegler who never responded. Our travel agent ended up trying to negotiate for us. We were looking for over $3000 refund (bridal makeup resulted in eye infection, entire bottom tier of cake was not served, guests did not get individual slices- rather 3 large slices placed in the middle of the table to be shared, did not get everything as promised in the DJ/MC package including bubble and fog machine, wrong flowers used in wedding gazebo corsages) and the hotel only offered $500.
Other issues: Over 40% of our guests had diarrhea/stomach cramps. Hotel would not accommodate double beds for non-couples, not even one of my friends who was 5 months pregnant, clearly showing, who was traveling with another friend. Groomsmen had to argue and complain in order to receive room service for the bridal party (they would not send more than 4 entrees even though there were 5 of them, 4 groomsmen plus groom) on the day of the wedding.
At the end of the day, everyone still had fun and the pictures are beautiful... but that would have been the same regardless which resort we went to.
Good luck to you and your cousin!