Answered by: Maulana Abdul Muktader
A man has two sons and one daughter from his first marriage. He divorces their mother and marries a woman from whom he then has two daughters. My question is, do the sons of the previous marriage become Mahram to the two daughters of the second marriage? Also, do the sons qualify to be Mahram to their stepmother in the Hanafi Madhhab?
In The Name Of Allah, The Most-Merciful, The Most Kind
Firstly the two sons do qualify to be mahram to their stepmother.
‘And do not marry those [women] whom your fathers married, except what has already occurred. Indeed, it was an immorality and hateful [to Allah ] and was evil as away.’
Secondly, the two sons are mahram to the two daughters of the second marriage as they are their sisters from their father.
‘Prohibited to you [for marriage] are your mothers, your daughters, your sisters,…..’
Only Allah knows best
Written by Maulana Abdul Muktader
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 لا يحل للرجل أن يتزوج …. بامرأة أبيه (مختصر القدوري ص.٤٧٠ ط. مكتبة البشرى)
وَلَا تَنكِحُوا مَا نَكَحَ آبَاؤُكُم مِّنَ النِّسَاءِ إِلَّا مَا قَدْ سَلَفَ ۚ إِنَّهُ كَانَ فَاحِشَةً وَمَقْتًا وَسَاءَ سَبِيلًا – 4:22
 ولا يحل أيضا أن يتزوج بإخته سواء كانت لأب وأم أو لأب أو لأم (البناية في شرح الهداية ج.٦ ص. ٣١ ط.المكتبة الحقانية)
حُرِّمَتْ عَلَيْكُمْ أُمَّهَاتُكُمْ وَبَنَاتُكُمْ وَأَخَوَاتُكُمْ ….. 4:23
وقال البغوي في تفسيره: سواء كانت من قبل الأب والأم أو من قبل أحدهما (ج. ١ ص. ٥٠٠ ط. دار طيبة)
This answer was collected from DarulIftaBirmingham.co.uk, which is run under the supervision of Mufti Mohammed Tosir Miah from the United Kingdom.