What is meant by the kin with whom ties of kinship must be maintained, and are the mother's relatives, such as her female cousins, considered among them, and is maintaining ties with them not considered an impermissible mixing [of genders] according to Sharia?

The womb that must be connected has been previously explained. There is no harm in maintaining ties with the daughters of the maternal uncle or paternal uncle, while observing the lowering of the gaze from them or addressing them from behind a veil, and avoiding private seclusion with them.