@MrsPramm - I actually don't see why not. I mean, I understand why it was made illegal in the past. Certain groups used to force very young women into marrying men who already had multiple wives. It was awful for the women and ultimately unsustainable because there simply weren't enough women for everyone to have multiple wives.
But in the modern world I think people should be able to design their families however they want as long as no one is being exploited or harmed.