jlpanian, have you done a search in the tags for OPP (one penis policy)? It's a tricky one. There are very few women that would conform to not being able to seek out other lovers while their lover has two. Actually, MOST people would struggle with that. After all, why should you be able to and not them. What is good for the goose is good for the gander type thing. Of course if this is a Dominance/submission thing then I would assume that your ladies are in it because they like to be dominated in this way. What worries me about polygamy is that the rights of women are not respected and of course children in religious polygamy in the new lately.
Anyway, there is some interesting reading on here about OPP. Hope you take a look