Siv, a member of the Scyre clan on the planet Parnassos, appeared in the Phasma novel and in a flashback in the Phasma comic.
Here’s the page with the Siv flashback from Captain Phasma, Part III written by Kelly Thompson, art by Marco Checchetto. 
Check out the entire list of women in 365 Days of Star Wars Women in the Women in Star Wars Index. It includes highlights from each post plus notes which posts include new 365 interviews with actresses, writers, artists, and more.
