In the 18 months that Sterling was gone, Hunter conquered the house and the women had his babies. Lucia saw through Hunter's scheme early on, but with Sterling gone she couldn't thwart Hunter by herself so she probably gave up and went home to Canada. (I thought there was a line that mentioned her leaving but I can't seem to find it.)
At a minimum Drew gave advice on hormones, as "Starling" explains to Brenna. I think Drew helped even more, most likely arranging for "Starling" to see the best doctors (including ones Drew used during her own transition).
EDIT: Here's the line about Lucia, right before "Starling" appears: