User blog comment:B214/Volume 22 spoilers/@comment-120.188.92.119-20160922152353/@comment-9595671-20160922233030

The ending is a cliffhanger on if Elmenhide will join him or not, and we still aren't sure if Bina's a placeholder like Irina or his actual queen.

We're pretty sure Bova is temporary since he says he knows Issei wants his peerage to be all girls, and when we consider the EX timeline mentions he has atleast 20 children, the rest of his peerage will likely be the remaining girls that make up his eventual harem.

I mean there is the case that one of the girls had more than one child, but it seems like they each only had one to keep things from becoming chaotic. Plus twins are already rare and technically Koneko and Kuroka's kids are the closest we have to twins.