Well can Erezi make more girls? Hmm, this game is huge. I haven't beat it after 20 hours.
Erevi does have 2 more daughters but they (& there brothers) are only place holders for now. Also as far as I know the Succubus was the only conception blessed by Nergal so the next 4 kids might be like the other children & have no real impact beyond running around the Tower. I'm not sure what Tink's plan is yet until he gets back to working on the Tower story.
I know that he apparently is planning to have Maghda birth a Half-Ogre daughter & Vixenatrix to birth a Half-Dragon daughter. But that is all I know about special daughters for now.
I have talked to others on here about Ziva birthing an Angel daughter as a counterpart to the Succubus (like a cupid or something) to which many have agreed sounds like a good idea BUT this is purely MY suggestion & there is no garentee Tink has seen or heard about my suggestion.