It's automatic, doesn't give tenants chance to argue or give sob stories, and manage how payments applied.

You said you live in Austin, no better way to learn than directly so, there is a syndication group Viking Capital LLC, that is buying/raising for a 252 unit property in NewBraunfels, about 45 min south of Austin, watch their webinar at their website below and they have an 82 pg slide show as well, then take a 3 hour trip to go see it, walk the property, go into office ask about the units available/leasing how the market is from the office staff, look around for quality of property/deferred maintenace needed then drive the area for other competitor properties.

Happy to connect and point you in the right direction.

ie: pricing software, listing platforms other than Vrbo and Airbnb, digital guestbooks, integration software, direct booking sites, camera subscriptions, other subscriptions etc.Then what percentage of all this software is it of your net profits?

If the wholesaler is assigning his contract to you, then GENERALLY you are paying for all closing costs and depending on the state you'd be paying for all the property taxes or prorated taxes UNLESS something in the contract stated otherwise (rare).If you're the end buyer and the wholesaler is looking to close GENERALLY they will pay for their closing costs with them as the buyer when they were direct with the seller, and then you'd pay your closing costs when buying it from the wholesaler "same" day.  

Is an expert in that area...PM me if you want his direct contact info.

I can more see it being legal if it was only applied to future lease agreements and not existing lease agreements.

You could have asked her directly and given her the benefit of an honest and open conversation about it, but you came on here and asked us strangers on the internet who don’t know her or you, so you get what you get like it or not. 

All expenses directly incurred for the ADU are 100% allocable to the rental unit. 

Be direct, be honest and stick to your process, if it you need to go through an eviction process it will take a long time if they are seriously and you are better starting early.