You know, I don't know that all living under the same roof again will solve their problem. I think when they were back in Utah, their arrangement was something that they had all agreed upon and were comfortable with. They each had their place within the family unit. I think the three of them could have lived that way forever.
They have made so many changes - starting the show, adding Robyn, moving to Las Vegas - which have thrown their family into a new and constant state of turmoil. Cody's solution is to have a baby with Robyn.

He is not capable of addressing the problems with his family as evidenced by him thinking he can patch things up with Christine like a high school boyfriend would by giving her a nice gift.
The wives are going to have to decide whether they can live this way. Cody is never going to change.
I agree completely!
When the show started out, they seemed comfortable with their arrangement. It certainly wasn't a lifestyle that I would choose or like, but it seemed to work for them. They were also part of a much larger Polyg. community, weren't they? So they fit right in with their culture, their kids were part of the Polyg. community, not completely different from all the other kids in their circle.
I think the two factors that changed the family for the worse were:
1. Marrying Robyn. I just don't see why he did that. Each wife had a place and they seemed to complement each other well. Janelle brought in money, Kristine was the at-home-mom, and Meri did a little of both and was also the Senior wife and organizer, it seemed. I have nothing against Robyn personally. She would probably be fine for Cody if she were his only wife. But if this huge family lives as a "collective" then I would think that they would look at each member's value for what they bring to the group. And, I don't mean to sound unkind, but I don't think that a non-working woman and three (soon four) kids add productivity to this family. This is in addition to the emotional stress of adding another wife.
2. Going on Television. This opened them all up to judgement, which I think they were not expecting. I think being on TV was a huge stressor for the kids. Being on TV is what cause them to be in danger of being prosecuted under the law. When they just kept the polygamy private, the authorities looked the other way. Kind of a "Don't ask, Don't tell" type of thing. They told. I can't believe they are surprised that they went on TV and admitted they are breaking the law, and the authorites had to act on it. Either keep it quiet, or boldly be ready to accept the consequences.
I think #1 and #2 are related. I am guessing that things weren't as rosy as they appeared in the first episodes, at least financially. The only reason to do the show, as far as I'm concerned, is for the money. So, the show would help them to make ends meet, but maybe the producers/TLC weren't sure the family was interesting enough to build a series around as it was. I admit myself that the first few episodes were fascinating- hearing how they handle the logistics of plural marriage. But after I realized that their day-to-day lives were kind of dull and tedious- like mine, the fascination waned. THe prospect of adding another wife to the family would add to the drama/ audience interest. So it would not surprise me if adding Robyn helped sell the show.
So, I think both factors were negative, but maybe they saw them as the only options.