Is it forbidden to combine two wives if the mother of one of them nursed the other?

If it is established that the aforementioned woman was breastfed by the mother of the questioner’s mother, then she becomes a sister to his mother through suckling, and it is forbidden to combine two sisters through suckling in marriage. Accordingly, the father's marriage to this woman is invalid and must be annulled, and the children are attributed to them due to the شبهة النكاح ( شبهة النكاح, 'doubtful marriage' or 'marriage under a misconception'). As for the grandmother being married to another man, this does not affect the fact that the two women are sisters through suckling; rather, it only makes that man a father through suckling to the aforementioned woman.