SOLVED. 3 siblings visit their Aunt and hear stuff about a boy in the woods. [s]

[Anamta]

There are 3 siblings, a 14? y/o boy, a 13? y/o girl named something very similar to Violet and a 11 y/o boy. Apparently their mom died or left them and from that day the oldest sibling had always been quiet and they lived with their dad who went away a lot to do portraits of people. I forget why, but they go to visit their Great Aunt in another city while their dad is away on a trip. She is young enough to be their mom and owns a really big house which she lets them stay in. They see this old man in the city when they go there and he tells them that there is a boy or monster in the woods, can't remember. later they find out that that old man has some history with the people who used to live in their Aunt's house or another big house.

Cover: There were the 3 siblings together. The oldest is in the middle and he has blondish hair that's kinda long and messy, the girl is beside him on the left and she has straight black hair and black eyes, the youngest boy is on the right and he also has black hair and eyes. None of them are smiling. Behind them are some trees and on the right you can distinctly see a pair of feet hanging down from a branch. It all looks kinda dark and gloomy.

I read it about 2 years ago from my public library and they only had 1 hardcover of it. Now, whenever I go back I can't seem to find it.

I also think that the title had the words boy and/or skinny and/or legs.

The end of the book if it helps. (view spoiler)[ They find out that their mom wasn't actually dead and that she was mentally disabled and thought she was a prince. The reason why their dad always went on trips was because he went to visit their mother and made portraits of the other mental people in that institution. (hide spoiler)]

[Tab]

The Kneebone Boy ?
Otto, Lucia, and Max Hardscrabble, whose mother has been missing for many years, have unexpected and illuminating adventures in the village of Snoring-by-the-Sea after their father, who paints portraits of deposed monarchs, goes away on a business trip.

The book has a wonderful illustration on the cover.

[Anamta]

Thank you so much for finding it!