Is it permissible, Islamically, for brothers to prevent their sisters from building on their shares of the inheritance, which was distributed 20 years ago, after all the brothers had forgiven their mother's share to the sisters, and now they deny this and want to force them to sell their shares, claiming that their husbands are strangers and have many children?

If the inheritance has been distributed and each heir has taken possession of their share, then they are free to dispose of it through construction or other means, and the other heirs have no right to prevent them, as they are disposing of their own property. However, if the inheritance was distributed as undivided common property, then none of the heirs has the right to dispose of it except with the permission of the others. As for the mother's share, if it devolved to the sons and daughters through gift or inheritance, and the males donated to the females, then if the gift was taken possession of, it is impermissible to revoke it. If it was not taken possession of, then it is permissible to revoke it. We advise the heirs to abide by the limits set by Allah.