Hi! I'm Kristina, nice to meet you! Is your Unnamed Female Relative still tbd? I've got two possible storylines that she could fit into, if you're interested! One would be a ghost--my dude's little sister who was one of The Academics. The other one could be the person Brand is currently dating, who could be another surviving family member he met after the tragedy.
Let me know if either of those spark any interest! Otherwise, the other characters you've got sound like so much fun. If Terry Crews dad was father to one of the Academics, then he's probably interacted with Brand. I think Brand would absolutely love him; his own parents are pretty strict and not very warm so he would be extremely drawn to an inviting surrogate father figure haha.