Don't they? Not the three or the four?
So how can Plural Marriage work, with Jim and Jill AND Sue?
Good question. Does the Bible give us any more hints?
Jesus prayed, in John 17:21 that they ALL may be one. That would have been at least 12, right? So, the idea of more than two being involved in a one-ness isn't totally illogical or impossible scripturally.
On a more practical note, some years ago I noticed raindrops on a window pane. One drop began to slowly move. It soon encountered another single drop and they merged, becoming a larger single drop. The two had become one. Shortly the new unified drop encountered another single drop and merged. Then another and another.
In each case, a unified, inseparable WHOLE merged with another WHOLE, and the two became one.
To me, that is a beautiful picture of marriage between ANY man and woman, whether THIS woman is the first one to merge with him or not. The end result is a new whole, inseparable, a family! Can anything be more beautiful?
Or natural? Lacking any resistance, it just happens so naturally! How much easier our lives would be if we would resist being separated, but joyfully embrace being united? Don't we, all to often, do the exact opposite?
One final lesson from the window: As the raindrop grew, it moved faster and faster. Not just the original one or two raindrops, but the whole united "family" of them. United, they got much further than any of them would have gotten alone!