Marriage... hmmm.
It is a very interesting problem. So, first, why? Why marriage? The obvious answer is: For the children, all the children.
Right now, only Tanya and Paveena are pregnant with Thomas children, that we know without a doubt.
Tanya hasn't made a decision yet, about being interested in continuing a relation or not, in spite of being very interested in Thomas. She was ready to take care of Anne alone, but she is still trying (AFAWK) to decide to accept Thomas's conditions and join the proto-harem as the first mother. Would marriage, obviously with several other women/mothers, be a decisive point for her? If so, either for or against? Tanya wants Thomas as the father of Anne, that we know for sure. We need more Tanya time to find the rest out.
Paveena is already married. Technically to "that guy", in her mind to Thomas. I don't remember if their child's gender has been mentioned yet or not, but she can't nominate Thomas as the father. Marriage isn't clear to even be an option for her. From what MoonBox has been saying, Paveena isn't really part of the harem. It is what it is.
So, the children as they stand right now, are protected. The mothers that we are aware of, wouldn't probably want or need a polygamist wedding.
After why, let's ask Who? Who would Thomas be marrying? Every girl? From Mama Mabel to Sophie? Just the 1st Harem? Just the younger ones? Just the older ones? We know that MB doesn't want the Mega-Harem, but a collection of smaller ones. So, who would he marry? I have no clue. Not to even mention that there are married women in the mix already (Natalia, the french girl that I forgot the name of, Jada, Paveena, Pryia, Karen and Jamila). So, what a fucking mess already.
Next up is When? Is this THE endgame? The "Lived happily ever after"? Or, is it made as a foundation for the Harem, having a succession of "marriages" as each girl joins? Or, as I mentioned in "Why" when they find out that they are pregnant?
I know, I know, I just asked a bunch of questions without giving any solutions. The thing is, I don't think any of us has the answers, only
MoonBox , it is up to him to know and decide if this, any of this, makes sense and happens, or not. And Why, And Who, And When.
We are talking about a plot point, it's all fine and dandy, except to make it make sense we need info that currently only MB has (AFAIK) so, it is rather irrelevant to theorize, dream or even take stands on how or where.
Do we trust that MB will provide a solution, either this one or another, that will satisfy our collective romancing wishes? I trust he will. You? It's up to you.
Peace