What is required when someone purchases two or more individuals from the spoils based on a presumed relationship that prevents separation, but later that relationship is found not to exist?

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If someone purchases two or more individuals from the spoils, calculated against their shared share based on the assumption that they are related relatives between whom separation is forbidden, and it is later revealed that no kinship exists between them, the purchaser must return the excess value to the spoils. This is because their value increases when separation becomes permissible. For instance, if two individuals were bought assuming one was the mother of the other, the ruling restricted cohabitation and selling one without the other, thus lowering their combined value. If it becomes clear they are unrelated, cohabitation is permitted and selling one individually increases their value, necessitating the return of the surplus value, similar to finding extra jewelry or gold with the purchase, or taking an amount of dirhams that turns out to be more than calculated.