Do the sister and mother by suckling have rights over the suckled, and is it obligatory to search for them?

The scholars have differed regarding the definition of kinship (rahim) concerning which maintaining ties is obligatory. Some said: It is every kin with whom marriage is prohibited (mahram). Others said: It is general to every kin among those who share lineage (dhu rahim) in inheritance. And it was said: Kinship (rahim) is of two types: general and specific. The general is the kinship of religion, and the specific is the kinship of blood relations from both sides of a man: his father and his mother. Thus, every Muslim with whom you share a general kinship (brotherhood of religion) has obligatory and recommended rights upon you. If there is a type of kinship between you and this Muslim, his right upon you is affirmed, even if he is not among the kin in the specific sense. Likewise, the rights of those with whom marriage is prohibited through suckling (mahārim min ar-raḍā‘a) are affirmed, and they are given precedence over others.