Is it permissible for a sister to cook the meat of the "wa'da" (vow/pledge) that is held for Sidi Abd al-Qadir, knowing that it is an act of shirk, and without eating from it, or must she refrain from cooking it, despite her fear that divorce may result from that?

It is not permissible to hold "Wa'dat" (Mawlid) celebrations, because they are innovated festivals, and because they involve exaggeration and are a means to polytheism, such as sacrificing to other than Allah, committing forbidden acts, and taking graves as places of celebration, which is forbidden by Islamic law. If the sacrifice is an offering to Abd al-Qadir, then it is a major polytheistic act that expels one from the fold of Islam. It is not permissible to eat these sacrificed animals, nor is it permissible to carry them, cook them, or distribute them, nor to cooperate in such an act. A wife is not obligated to obey her husband in disobeying the Creator; she must refrain from cooking and explain the impermissibility to him. If the husband slaughters for the dead or invokes them, it is not permissible for the wife to remain with him until he repents. However, if the slaughter is for consumption with the mention of Allah's name and is not a vow to a saint, then the sacrificed animal is not forbidden, though one should not assist in it because it is an innovated act. If the wife fears harm to herself, there is no sin upon her for cooking, though it is disliked, and she should try to reach an understanding with her husband.