Stanny Lyn was 100% unnecessary for this trip. Even they claimed they'd just been spending "so much time" doing "family stuff" they hadn't filmed much for some of the days. Which, if they weren't filming, then they wouldn't need Stanny around to make sure their kid stays alive. The nanny was hired because they're "soooo" busy with their "job", right?
Even if they wanted to go watch the sunset and it was after J$ had already fallen asleep, they could have just waited until "the cousins" got into town - then either or both Dim's brother and the SIL could stay at the house with their kids and J$ while these two shitheads waddled over to the beach to stare directly at the sun. And since Manny Matt and his partner were coming too, heck, they could have left J$ with Manny Matt who probably would have given the kid raspberries while these two searched for puka shell necklaces and tshirts and olive oil.
Ginn of course would counter with her usual nonsensical, "well, her job is full-time so we had to bring her with us". Maybe you shouldn't have made her job FT then if you have to drag her on vacations, with that logic. Oh what's that? She asked for the job to be FT? You should have said no and found AN ACTUAL LEGIT NANNY.