What is the ruling on two men agreeing that each will marry his sister to the other?

Shighar marriage is forbidden by Islamic law. It is when a man marries off his female ward to another man, in exchange for that man marrying off his female ward to him. This contract is invalid, whether a dowry is mentioned in it or not. Shighar leads to forcing women to marry those they do not desire, depriving them of their dowries, and increasing disputes. The remedy for those who have entered into a shighar marriage and wish to proceed with the marriage is to renew the contract with a guardian, a dowry, and two witnesses. However, if they do not wish to proceed with the marriage, the husband must divorce her.