Thank you all so much for your input...
Our RM is coming to the property at the end of the month (first availability) to discuss the issue with the cleaner. If she admits to posting the review, then she will be terminated. If she denies it, then we are just adding the incident to her ever-growing personnel file.
As for the previous termination, we did everything the way we were supposed to. We let her go because she, to be frank, just was not good at her job - even after coaching. She also openly discussed that she was actively seeking to increase her side jobs so she wouldn't have to work here anymore. So, we let her go and replaced her with a far more skilled LC with a growth plan within our company. She claimed we fired her because she had a baby and needed breaks to express milk - not remotely true. The RM who fired her didn't even know she was breastfeeding until we got the complaint! We worry that if we fire the cleaner (I'm in PA - it's an "at-will" state, so we don't necessarily need cause) we'll end up with another bogus suit on our hands. This time, it would likely be ageism - our cleaner is mid 50's, so it's likely that her replacement would be younger than her. We know that she was involved in a lawsuit with her previous employer after she stopped working there. When did everyone become so litigious????? (I know, that's a whole different conversation......)
It's interesting that 'who started first' was brought up a few times...I was promoted to Manager, and was training with the previous manager, when she was hired. So, we both started right around the same time. She wasn't used to answering to a different manager, and then had to adjust to me. I can see why you'd ask that, though, because she behaves as though she was here longer. In her job history, every other position she's had has been supervisory/management in some field, so I really think that regardless of everything else happening on site, she just needs to feel in control, and I won't let her control me.