>>101777749Hiring one or two former idols per gen seems fine to me. It might even influence the others in the group or help them get an idea of how things work or what to expect. They all talk and meet each other long before they debut.
Nene is also a former idol, and no one ever complained about that. FUWAMOCO and Kiara as well. Although they were from much smaller groups than Vivi and Riona. Vivi and Riona were the real deal.
I think there might be a couple other members that were in idol groups before hololive, but I can't remember. I think maybe Moona was also in some kind of group.