Is it permissible to propose to a non-Muslim woman who intends to embrace Islam, on the condition that she does not declare her conversion, wear the hijab, or perform prayers until after marriage? And how would the proposal be conducted if that were permissible?

It is permissible for a Muslim to marry a chaste woman from the People of the Book (Jewish or Christian) through her non-Muslim guardian. If the girl embraces Islam, the Muslim judge or his representative undertakes the marriage contract, because a non-Muslim has no guardianship over a Muslim woman. The Muslim should strive to invite the girl to Islam, and there is a great reward for him in guiding her. If the girl embraces Islam and fears the persecution of her family, there is no sin upon her in concealing her Islam and performing prayers secretly. After marriage, the husband must obligate his wife to wear the hijab, whether she is from the People of the Book or a Muslim. Attention must be paid to the danger of residing in non-Muslim lands to a Muslim's religion and morals.