daughterins
Daughterins is a term used to refer to the daughters of one's children. This means the female offspring of a son or daughter. The term is less common than "granddaughter," which specifically denotes the daughter of one's child. While "daughterin" is not a formally recognized English word, it can be understood through its etymological components, "daughter" and "-in" suggesting a connection or relation similar to how "son-in-law" or "daughter-in-law" are used.
In some contexts, "daughterins" might be used informally to distinguish between the daughters of different children.