Co-wife

If a co-wife had sought the lives of those three of thine.

In fact, [Ayesha] was more jealous of Khadija, the dead wife, than she was of any of her living co-wives.

If the senior wife decides to make life unbearable for her co-wife and their husband, she is likely to succeed in forcing the newcomer to leave.

In other words, polygamous societies differ markedly with regards to allowing kin, especially sisters, to become co-wives. Sororal polygamy is practised in some societies because it is believed to foster greater cohesiveness among co-wives sharing values and norms, whereas it is specifically forbidden in other polygamous societies.