See if it works. It’s been a while since I did this. I mean, it’s been a while since I last logged in to the game to do anything beyond one Warfront per cycle for the Elite Transmog set. It could be bugged. I hope not though.
To really get your bang for the buck, use your Narcissa’s mirror toy on your cat prior to casting /sit.
Or, use your magic pet mirror toy on yourself, transform into your cat, or whatever pet you have out, then use the narcissa’s mirror on your cat. If you have enough toys to change your own appearance, the possibilities are near endless of who or what could be sitting on your lap.