Last season, I watched every episode of "Big Love" about a polygamist family who had to hide their living situation. They were mormons, and in Utah.
Differing from my perception that the polygamist families there ALL live in compounds far from other people, this family lived right in the middle of an suburban area, and was a prominent businessman.
Actually, the husband HAD been raised in one of these polygamist communities, but (to answer the question about how polygamy can work if males = females) he got literally thrown out when he became a teenager. This was discussed in another thread a while back. It turns out when a boy reaches a certain age, they are a threat to the Elders, who take all the wives....so, a teenage boy will be driven into a city, and just dumped there to make his way. I'll try to find that link.
Now of course Big Love is a HBO work of fiction, but I'm sure there's truth woven in there.
Honestly, it seemed really REALLY difficult maintaining a family like that. This guy Bill (played by Bill Paxton), because he had to hide the fact he had 3 wives (and their children), owned 3 separate houses, all next to each other. Looked very normal from the front, but in back, all the backyards were linked....He would always enter into the 1st wife's house from the street, then, would go to whatever house he was going to spending the night at.
The 3 wives had monthly business meetings, to discuss household matters re childrens activities, budgets.....and write up a schedule of what nights Bill was going to be at each house. It seems that even if they had all lived in one house, they still would have had these meetings, to decide which bedroom Bill would go to.
It was very important to the family that Bill not show favoritism toward any one wife, and when he was with one, the others where not allowed to interfere.
2 episodes come to mind regarding the sexuality....In truth, all the wives were very modest about discussing sex and it was work to not become jealous.
In one episode, it was the start of a day, apparantly when Bill made the switch from one house to another. Before he left for work, he had to go back to the house he'd been at the night before, because he forgot something....when he went there, he ended up getting aroused by the wife he'd just been with, and they had a quickie....the wife whose day it was walked in on them, and she was irate..."THIS IS MY DAY"!!!
In another episode (actually several) Bill and his first wife both started reliving the days when it had been just the 2 of them, and they were feeling especially close. They couldn't get enough of each other, and where meeting each other at noon at a local hotel. Both were expressing guilt over their "affair"
So, from what I can see, it wasn't some free for all and took a lot of effort on everyones part to do it right.