Answered by Ustadha Zaynab Ansari, SunniPath Academy Teacher
I am a revert of 2 years. Alhamdullilah! But before I reverted I made a lot of mistakes. I fell pregnant to a person I hardly knew. After this fact I went back to my ex-husband and he took her as his own and thinks of her as his daughter. At the moment she is living half a year with him and half a year with me. She is only 4 years old. I made a promise that I would not take her from him until the year 2007. He has since reverted and has just married again . His new wife doesn’t want our children. My questions are, is he mahram to her? And is it haram for her to live with him and her half siblings? I would really love to have her with me, but taking her away from her siblings is a big worry.

In the Name of Allah, the Gracious, the Merciful.
Praise be to Allah.
May the peace and blessings of Allah shower upon our beloved Messenger.
Dear Sister,
I pray this message finds you and your family in good health and spirits.
This situation is a delicate one, so I advise you to proceed with much thought to everyone’s wellbeing.
It sounds like your ex-husband knows that he is not the biological father of your daughter, but has chosen to take her in anyway. His attitude is most commendable.
Even though he is not your daughter’s biological father, he is still her mahram provided he had sexual intercourse with you. Thus, it is impermissible for him to marry her and he must treat her as if she is his daughter. [Reliance of the Traveller, m6.1]
It is not unlawful for your daughter to live with her stepfather and half siblings. However, you mentioned the fact that he has remarried to a woman who does not want your children. Please think of your daughter’s wellbeing. She may be far better off living with you, and visiting her stepfather from time to time. I would definitely suggest that she come to live with you by the time she enters puberty.
I also suggest you and your ex-husband take this case to a qualified local scholar who can suggest an arrangement that is to the benefit of all. Remember: your daughter’s wellbeing is paramount. Since it sounds like your ex-husband is the only father she has ever known, it may be wise to encourage her to maintain ties with him, provided that Islamic decorum is observed.
Please see the following related answer on stepfather-stepdaughter relationships:
Covering in Front of Non-Muslim Stepfather
http://qa.sunnipath.com/issue_view.asp?HD=3&ID=2213&CATE=340
And Allah knows best.