What is the ruling on a man marrying a girl whose sister his own sister breastfed for a long time and they had children, and what is the ruling concerning these children if the marriage is impermissible?

The question can be interpreted in three ways. If the intention is that the woman was suckled by the man's sister, or that she was suckled by his sister, and the prohibitive suckling (five full breastfeeds) is confirmed by the testimony of those whose testimony is acceptable, then they must separate immediately. This is because she becomes unlawful for him due to suckling, and the marriage contract is annulled upon the confirmation of suckling. As for the children, they are attributed to their father if the contract was valid and he believed in its validity, and they have all the rights of children. However, if the intention is that the woman he married suckled his sister, then it is not unlawful for him to marry her, and her suckling his sister does not make her unlawful for him.