SOLVED. Y/A Fantasy probably it took place in a big house that turned into a big boat where the three main characters meet mean mermaids with their male adult relative

[Aerin]

I listened to the audio book easily 10 years ago and the book itself is probably way older than that. I wanna put the timeframe of the book before the information age maybe? There are three main characters, three siblings a boy and a girl and their like 3 year old brother. Theres a dumbwaiter in the house that will fullfil requests to the best of its ability. The house turns into a gallegon of some sort. The ship meets mermaids, but theyre like peter pan mermaids and are kinda mean.
(Possible spoilers?)
The youngest gets taken in the dumbwaiter to the entity in the kitchen and is changed when he is returned. He talks older than his years
One of the mermaids (who the girl main character was trying to be friends) with sacrifices herself to save the boat

[Aerin]

Whoops someone already had a post about this. Feel free to delete. Its The Drift House by Dale Peck

[Rosa]

Posts aren’t deleted here. Please don’t delete your first post yourself, either. They all add up to one beautiful chorus of reconnection and recollection of books for everyone.
Kudos for actually finding your book yourself here, in this group! I’ve never actually seen someone do that. How did you find it?
The Drift House: The First Voyage for the link.

[Aerin]

I narrowed it down to YA and then I searched for the keyword "ship" I got lucky on the second page.