Is it permissible for a father to sell the house to give his son his due in marrying his siblings and educating them, then divide the remainder equally among the children (the sister receiving the same as the brother)? And is it permissible for the son to buy the house and take his share from the remaining price?

If a brother builds a house for his father as a donation (tabarru'), it becomes the property of the father, and he has the right to sell it. It is permissible for the brother to buy it at a mutually agreed-upon price.

However, if the brother spent money on his sister's marriage and his brother's education, and this was not a donation, then he has the right to reclaim the money from those he spent it on, or from his father if the father guaranteed that to him.