Is it obligatory to maintain ties with one's sister's sisters through rada'a (nursing/fosterage), or only with her (the foster sister) herself? And is it permissible to cut ties with them if their husbands are unwilling for such ties to be maintained?

Scholars differed concerning the definition of the womb (kinship ties) that must be maintained. The most authoritative view is that it is of two types: a general type, which is the kinship of faith, and its duty is to show loyalty to the people of faith and support them; and a specific type, which is the kinship of relatives from both the father's and mother's sides, and its duty is to fulfill their specific rights and more, such as providing financial support and checking on their well-being. Based on this, the sisters of a sister through fosterage are not considered part of the specific kinship, and it is not obligatory to maintain ties with them in the same way that specific kinship ties are maintained.