Is it permissible to marry one's daughter and then divorce her, so that her mother becomes unlawful for the husband, enabling him to help her?

We advise against proceeding with marriage without genuine desire. The issue of khalwa (private seclusion) can be resolved by the presence of another person or if the place does not ensure privacy. Some scholars are of the view that khalwa with an elderly woman who is not sought for marriage is less severe in judgment, but it does not fall outside the general prohibition of khalwa with a woman. Marriage conditioned on divorce or agreed upon beforehand is invalid. As for marriage with the intention of divorce without a condition, the majority of scholars deem it valid, while the Hanbalis have invalidated it.