I doubt it would be a problem so long as the room type you booked is for 2/3 guests. If it's just for 2 then they might get fun.
Lot of Families stay at Mangrove, so they might just be ignoring you?
Treasure Island isn't that much further and I would guess a little cheap, on a big beach and close to the floating bars.
You can call Mangrove, or chance it and just rock up and ask before you check-in. If the answers no carry on down to TI.
Or, just go to TI!
Yes you are right, they might just be ignoring me if they are family friendly. It's a shame as I am a well behaved guest, just might wind up back with two ladies one night who knows! I've booked into Treasure Island and will post about how it works out.