I've read that the actress, Sara Mitich, was having an allergic reaction playing Airiam in the first season and the role was played by a different actress, Hannah Cheesman, in season two. What I haven't been able to find is whether Nilsson was created because the producers felt bad for Mitich or that if they had planned out the loss of Airiam and intended to replace her with Nilsson. If it is the latter, perhaps they had also mapped this out for her.
In any case, I hope that there is mention that this is a young crew with a severe lack of experienced officers, especially given the recent loss of Nhan, who is a Commander.
If I was writing this, I'd have Willa step in in an acting role and mold her as a tutor for the younger officers.