1. Welcome to the Scope Creep club.

2. I'm not a fan of the idea of following two characters' stories in the same novel and not ever having them meet or have any sort of connection with each other within the scope of that book. My thoughts are, you could either write two separate books, one about each character, or you could handle the secondary character's back story through flashbacks in the 2nd book. Just my suggestions. But I do feel like if I were following 2 separate characters in the same book and they never connected, I would feel unsatisfied, like I'm missing some piece of the resolution.

Cheers,
Michelle