Husband insists son from previous marriage resides with second wife
15-2-2017 | IslamWeb
Question:
Assalaamu alaykum. I have a question regarding a man whom I would like to marry. He has kids from his previous marriage. I have not been married and have no kids. At first, we agreed that the kids will come to live with us after two years, but he subsequently changed his mind and insists that his son moves in with us as soon as we marry because he discovered that his son is sleeping on a couch where he is currently staying (with the ex-wife). My question is: can this man do this now although we already made a verbal agreement?
Answer:
All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad 
is His slave and Messenger.
As long as the marriage contract has not been concluded, none of the conditions are binding. Please refer to fatwa 87444.
As far as you are concerned, you have the choice to either accept this condition or refuse it. These conditions are not binding before the marriage contract.
However, if the marriage contract has been concluded, then he (the husband) must fulfill that condition to you, and you have the right to refuse that the child resides with you, unless the child is very young and has no one to take custody of him, i.e. there is no one eligible for that, in which case you have no right to refuse.
The book Bulghat As-Saalik, which is one of the Maaliki books of Fiqh, reads:
“In regard to the permissibility of refusing, he (the author) gave an example of a young child who belongs to either of the spouses, and the other spouse did not know about this child before concluding the marriage contract, and this child has someone to take custody of him; in this case, the other spouse has the right to refuse that the child resides with them. However, if there is no one eligible to take custody of the child, then the other spouse has no right to refuse that the child resides with them regardless of whether that spouse knew about the child before the conclusion of the marriage contract or not.”
However, we advise the spouses to try to reach a mutual understanding as much as is possible.
Allah knows best.