Hmm....I dunno.

Moze said his dad was strict....Trellis is strict. But, not to be racist, how could a white young woman and a pale elf have a dark skin child? Hmm.

(To the comment above)

Maybe adoption? The things that Moze's dad told him, that sounds a lot like what an older Trellis would say. "Don't get stuck in the past, focus on who you're going to be tomorrow."

Idk, there is just no tension between trellis and Emily.

Literally the description of Moze’s dad sounds like an older Trellis lol, in book five we see that Trellis has finally learned to let go of the past and focus on the future, Moze mentions this too, “to not be stuck in the past and focus on who you’re going to be tomorrow”. Moze seems to be adopted too since he’s from a completely different planet too, maybe Emily and Trellis can’t have children and decide to adopt?