a booster for a car? No we didn't take one. The taxi we took to Little Divi Beach, and the Sunny Liston tour didn't have seatbelts that I saw.
As for the bedrails and jogging stroller we called
DCL and asked them to reserve them. Then when we got on board we wanted another bedrail and our room stewardess brought one within the hour. They must have plenty on board because I heard someone at guest services onboard asking for them.
They both came in handy, although we brought the jogging stroller to
Castaway Cay and it was a waste since once you get on the island they have those big wagons you can just take and use for the day.