Does a father become a mahram to his second wife's daughter from her previous husband, knowing that the second wife breastfed the father along with his sister from his father's side?

The rule of breastfeeding is that any two individuals who breastfed from the same breast are siblings through nursing, and therefore, neither of them is permitted to marry the other or the other's child. Based on this, if your grandfather's second wife breastfed your father, then your father becomes a brother through nursing to her daughter from a previous husband, due to their shared breastfeeding from her breast. It is a condition for the prohibition to be established that there be five full, satisfying breastfeeds, according to the preponderant opinion.