Will my husband's wife's prayer against me be answered because I married him, and is my prayer against his mother considered an act of disobedience to parents?

Allah has permitted polygyny for men, provided they are able to fulfill their obligations, and there is no disagreement on this matter. The prayer of a co-wife against her because of her husband's marriage does not harm the wife; rather, the co-wife would be a transgressor, and aggression in supplication prevents its acceptance. A wife's prayer against her mother-in-law for injustice is not considered disobedience to the husband; rather, it is a seeking of one's right. However, it is preferable to refrain from such prayers and instead pray for reconciliation between hearts.