Is it permissible to marry a girl whose brother was suckled by my sister's mother, not by my own mother and father?

If the girl's father suckled with your sister, not from your mother, and not from your father's milk, then his suckling does not affect you if you did not suckle from the same woman, and you may marry his daughter. However, if he suckled from your mother, then he is your suckling brother. In both cases, it is stipulated that there must be five full sucklings before the child completes two years of age.