What happens regarding prohibition if a man marries an adult woman and another man marries a minor girl, they divorce each other's wives, and subsequently the first man's (now divorced) adult wife breastfeeds the second man's (now divorced) minor wife with his milk?

Primary text

If the adult wife breastfeeds the minor girl, the adult woman becomes forbidden to both men, and her marriage is nullified. If the husband of the minor girl had consummated the marriage with the adult wife (before the exchange), she becomes forbidden to him, and her marriage is nullified. Otherwise, she does not become forbidden to him.