Hi, I've been scouring the internet to no avail and hyperfixating on this and I'm about to go crazy. Does anybody here know how to make a mirror reflect your sim in a custom create-a-sim background? I've found so many walkthroughs about how to make a simple static image into a CAS background, so I'm good on that part, but nothing about the mirrors.
I've got such a cool variety of setups ready for custom backgrounds but no idea how to make them work yet, because my overachieving self put mirrors right next to the sim's standing place in every one of them.

SOS<3