I think some people are missing something, or maybe I just am, about Stacy.
She lets slip and accidentally calls her grandmother, mom, meaning she doesn't know her mother, or the older lady is actually her mother, whether biological or not. I think that the memory the MC has of Stacy really is her from his childhood.
Now relation wise there could actually be a few logical Scenarios.
He could have spent time with her in her family as an adoptive child before Azel. I think I said this elsewhere and I could be wrong but it's just a feeling I have.
She could be a childhood friend he's forgotten, I think this is the most likely.
She could be a relative and Wendy actually had another child and Stacy's older mother is actually Wendy's Mom, think this is least likely.
It'll be interesting to see where the story goes with her. She's the current dark horse in the dynamic that I like to speculate about.
Sorry ahead of time if I'm rehashing old conversations it's hard to keep up with this thread since it's sooo active.