While it is not a offered option in Urban Shadows, many other PbtA games have an Advancement choice that lets you make a second character to play at the same time. I have used this and never had a problem with it, though it is not a common choice, possibly since many find it strange or too much work.
I have no problem with any of you piloting an NPC, as much as you like (so long as it does not break the story). If anyone else wants to try similar, we can arrange it.
On the other hand, if anyone is not satisfied with Drgwen playing two 'characters', let me know and we can phase it out.
Circe is not a PC, she does not have Stats and can not roll dice. They are also not fully under the player's control, since we share narrating with her.
If she ever does need to roll we may have to revisit this issue, but I think it is fine as it has been so far. Giving her a Playbook would be a big deal, the Urban Shadows playbooks are rather impactful on the story, so we would need to talk about it first if we want to. Giving her a few Stats and a Move or two down the line may be interesting, if it comes to it, but those could also play out much like most NPC abilities.