Is my husband a mahram for my brother’s daughter whom I brought up?

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Check below answers in case you are looking for other related questions:
Does she have to uphold ties of kinship with her husband’s relatives even after divorce?
His grandfather’s daughter is also his paternal uncle’s wife

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Is it permissible for a woman to uncover in front of her husband’s mother’s husband?
Does she have to uphold ties of kinship with her husband’s relatives even after divorce?
His grandfather’s daughter is also his paternal uncle’s wife

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