I think talking to them might have changed. I just finished the fight 15 minutes ago, and they came to her aid. I killed Auntie with a fireball and they all remained hostile. I am not sure if was changed or if it was my strategy.

I put down a fog on the ground on top of my group. Threw haste spores on the outer rim of the fog. I would run out of the fog, into the spores, get my 2 attacks, then run back into the fog and hide. It seemed to work pretty well, the one archer was able to attack into the fog from a distance. But everyone else didn't know what to do. I repeated this until I finished off Aunti with a Fireball.

After Auntie died, all of the Masked Servants stayed hostile. I have no idea if it was changed or if I bugged out the trigger for them returning to neutral. I'll do some more testing on it.