Story identification: a boy goes to a boarding school which is secretly a wizarding school [duplicate]

Question

I remember reading a book from the library, probably between 2005 to 2015. I read the book in Hebrew but I think it was probably translated from some other language (I guess from English but this is a pure guess).

What I remember about the story:

• The main character was a boy, living alone with his parents (from the another point it follows that he has brothers or sisters, which presumably didn't live with the parents anymore).
• The boy didn't like his parents very much (but I don't remember how it was showed); the father did complained that today he cannot punish the boy like how he (the father) was punished by his father (that is, the grandfather).
• The father uses a wheelchair, I think it was mentioned that it was a result of one of those punishments he (the father) got.
• The family gets a brochure about a boarding school and they decide to send the boy there. This boarding school is actually a wizarding school but this fact is revealed only near the end of the story - until then even the boy, while attending the school, does not know that.
• In the way to the boarding school, the boy meets another 2 children (perhaps boy and a girl but I'm not sure) which too go to this school. They discover that each one got a wildly different brochure, and this fact, along others, makes them little suspicious about the school. I think that it seems that each one got a brochure that would maximize the chances they will be sent to the boarding school.
• In their journey to the school, they meet a (maybe) priest in the train which asks them where do they go. When the priest hear the name of the school he faints.
• After they reach the school, there is a meeting of the boy and the principal. The principal notes that the boy is a seventh child of a seventh child, and the boy does not understand why does it matter.
• The principal also notes that now there would be 169 pupils in the school, and that 169 is a very special number. It is stated (I am not sure whether in a footnote or in the rest of the story) that 169 is special because 169 is 13 times 13.
• In one of the classes the students make human sculptures. Then the teacher adds (if I remember correctly) real hair to the sculpture.
• It is stated that the English teacher talked about Shakespeare as if she knew him. It is a clue that she lived forever or something like that. There were also other strange teachers but I don't remember how.
• At some point, few days before the boy's birthday (or perhaps in the birthday?), he decides that the school is too creepy and tries to run away.
• In the boy's birthday, the school principal catches the boy and reveal him that the school is a school for magic; the boy has a choice between accepting this or to die. (Perhaps it was the other way around - the boy had a choice between accepting a secret or die; and then the secret was revealed).
• It is said that any student in the school is only revealed about the school purpose in their birthday.
• In the epilogue, the boy returns to his home. When he comes home he freezes his parents (in the sense of making them not move) and creates milkshake out of thin air.
• At least in Hebrew, the book was named after the boarding school, and the name in Hebrew was something like "בית אשמדאי" (translated to English: House of Asmodeus). I tried searching that in Google, with no avail.

Answer 1

Groosham Grange by Anthony Horowitz seems likely. From this review:

David Eliot is 10 year old boy who does not know he is a sorcerer until his father recieves a strange letter in the mail inviting David to a special school. David's parents are far worse than the Dursleys, and so Groosham Grange makes a welcome change for David, except that there are clearly strange things going on there. Students disappear from the library, and the teachers don't seem to be human. Groosham Grange is filled with puns and oddball humor- an Anthony Horowitz staple. When I met Anthony Horowitz a few years ago, he said that David Eliot was the character most like himself, and that David's bad report cards from school were based on bad report cards that Anthony himself had received as a boy. I recommend this book!

This review mentions the differing brochures and the birthday aspect:

After getting expelled for poor conduct he is offered a place at Groosham Grange, however this proposal was not by coincidence. On route to his new school, he befriends Jill and Jeffrey and through their discussion it seems that they had each received a letter with differing information to portray this school ideally for their parents .... Jill and David plotted their escape for help as they knew they were in a place where everything was abnormal. However, on all attempts they failed and on their 13th birthdays, they were converted to the magical side at Groosham Grange.

David's father is Edward:

Edward Elliot is introduced as the psychotic, abusive father of protagonist David Elliot. Edward idolizes his deceased father, seeing him as the embodiment of good, when in fact his father was the complete opposite. Edward takes pride in the caning his father achieved, saying "It never did me any harm!" and "It made me the man I am!" when in fact he cannot walk because of his caning and is in a wheelchair. As Anthony Horowitz says, this would be sad except Edward hated walking in the first place and loves his wheelchair.

Found with a search for site:goodreads.com magic school "seventh son"