User blog comment:B214/General Discussion/@comment-1359322-20161106045332/@comment-27083298-20161108233630

The only confirmed wives are

1. Rias 2. Akeno 3. Asia 4. Xenovia 5. Irina 6. Rossweisse 7. Koneko 8. Kuroka 9. Elmenhilde 10. Le Fay

Issei had probably made more children due Xenovia and Kuroka wanting more children and Akeno mention she would bear as many children as he want.