Two sisters decide they want to have babies. But the thing is they don't want their first child to be with their own husbands. They switch husbands for the baby making.
Two sisters decide they want to have babies. But the thing is they don't want their first child to be with their own husbands. They switch husbands for the baby making.
I seem to remember a story where four non related college students (two guys and two ladies) formed what was a de facto group marriage.
The guys each had one child with one of the ladies and a set of twins with the other one and ended up marrying the later one and raised their stepchild as their own kid.
It could be that the parents were two sets of step-siblings each with a guy and the lady that was not their spouse.