You know, this is some shit that I expect when dealing with some shady asshole on ebay, but LMG?
Bro... Are you ok?
I always wondered if Linus was actually a slimy POS, but this Billet Labs situation has cemented it for me. If you haven't watched the Gamers Nexus followup video, definitely watch it.
There's a million different ways, most trans people don't immediately change their last name so you can use that. Or you can refer to something that Emily did to provide context. I'm sure if you stop and think about it, you can figure out a few more ways too.
At the end of the day it's not about making it easier for you to understand what's going on at the expense of disrespecting her. She's asking for you to use her name, so stop calling her something else.