Is it permissible for one to marry his step sister’s daughter if the step sister is from different mothers but same father.?
The ‘step sister’ you refer to is actually his real sister (consanguine sister). She is a Mahram relation to him. Hence, her offspring will be regarded as his Mahaarim as well.
Hence, he is not permitted to marry her.
and Allah Ta’ala Knows Best
Mufti Muhammad Kadwa
CHECKED & APPROVED: Mufti Ebrahim Desai (Fatwa Dept.)