Is it permissible to attend a wedding held by relatives who sell alcohol, given the mother's insistence on going?

The treatment of people engaged in wickedness and disobedience varies according to the prevailing benefit. If shunning them is effective in deterring them, then they must be shunned. Otherwise, it should not be done, due to the forbidden breaking of ties. Accepting a Muslim's invitation is obligatory, especially for a close relative, unless there is a forbidden act involved, such as alcohol, as the Prophet, peace and blessings be upon him, forbade sitting at a table where alcohol is consumed. Therefore, one must accept the invitation if there is no forbidden act, or if you can denounce it. As for eating from their food, it is not permissible if their sole source of income is alcohol. Otherwise, it is permissible, unless the food itself comes from ill-gotten wealth.