Is it permissible for the wife to contribute to household expenses an amount equivalent to the costs of her children from a previous husband, and to contribute to half the expenses of building a shared house, knowing that her non-contribution may affect the inheritance of the children?

A husband is not obliged to financially support his wife's children from another man. Their financial support is obligatory upon their mother if their father is deceased or incapacitated. There is no harm if the husband shares household expenses with his wife in an amount equivalent to her children's maintenance. There is also no harm if he requests her to participate in the costs of building the house to the extent of her share, but not as an obligation. However, obligating her is not permissible unless the land cannot be divided or benefited from except by building on it. In such a case, it is permissible to obligate her either to participate in the construction or to sell her share to someone who will participate. It is stated in "Al-Kharshi" that if two partners own an indivisible property that requires repair, and one of them refuses, he is ordered either to carry out the repairs or to sell his share to the one who will.