I don't recall reading about her. She wasn't in Mab's Sidhe legion that got glamoured, she wasn't in Molly's reinforcements.
Yeah, I'm pretty sure Lea was being Mab's proxy at the Outer Gates.
Because early on in the story, there was a big assault at the Outer Gates, evidently in coordination with Ethniu's assault (Harry remarked on it being telling, who (among the factions in Chicago for Peace Talks) appeared to notice & understand the implications); everyone seemed to think that (if all those Outer Gates forces were not urgently engaged) Winter could reasonably have shut down the entirety of the Fomor assault with no other help (though of course Ethniu & the Eye would always need something exceptional).