Is the marriage contract valid for a couple who divorced and agreed to return on a temporary condition for the purpose of providing for the children?

The financial support of children who have no wealth is obligatory upon the father, whether the marital relationship is ongoing or there is a separation. It is not permissible for the husband to make the financial support a condition for his wife's return, for marriage is based on permanence and does not accept temporariness. If it is contracted on the basis of temporariness, then it is an invalid marriage.