Is it permissible to marry the daughter of a sister's husband if she is not the sister's own daughter?
It is permissible to marry her because she is not among those women forbidden in the verse from Surat An-Nisa: (Forbidden to you are your mothers, your daughters, your sisters, your paternal aunts, your maternal aunts, your brother's daughters, your sister's daughters, your foster-mothers who suckled you, and your foster-sisters). She is not the questioner's sister's daughter, so there is no reason for prohibition here based on lineage, suckling, or affinity.
Summarized from the full answer at Ftawy · reviewed Sep 2, 2026
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