ANSWER:

The children born out of wedlock of your sister are your kinship as she is their mother and gave birth to them!

The children born out of wedlock of your brother are not related to neither him or you. 

I wanted to ask if a person has a brother or sister and rhey married to a non Muslim are their kids count as nephew and nieces or no ? Especially if a muslim women married a non Muslim man are her kids nephew and niece of the maternal side I know the relationship is invalid but what about the kids?

Illegitimate children & Lost property | September 21, 2021 5:40 pm
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My friend found an lost iPhone with no pin in his car. He does Uber so maybe customer dropped it. He wants to sell iPhone. Would this classify as stealing/theft in Islam? Is it permissible to sell?
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QUESTION: Please what is the ruling of the inheritance of a child born out of wedlock.