Must a Muslim woman cease spending on her underage children after converting to Islam, and does the ruling "Islam obliterates what came before it" apply to the children as it applies to the husband?

If the wife of a disbeliever embraces Islam and her husband does not, and her waiting period ('iddah) expires, the marital bond between them is severed. Her marriage is not valid without a guardian (wali). If her guardians are disbelievers, then the Muslim judge (qadi) is the one who marries her. If there is no Muslim judge, then a just Muslim man marries her. The initial marriage contract should be annulled in the courts.

As for the mother's financial support (nafaqah) for her needy children, it is obligatory upon her if she is affluent and the children have no one else to support them. However, scholars have differed regarding the obligation of support for relatives when there is a difference in religion. The Hanafi, Maliki, and Shafi'i schools obligate it, unlike the Hanbali school. Therefore, it is more cautious and preferable for the mother to provide financial support for her needy young children to avoid the disagreement of those who obligate support for children or parents despite a difference in religion.