If I fail to bring him value I doubt he will continue to mentor me. 

In Mecklenburg County (home to Charlotte) a duplex/triplex/etc. is required to have fire separation that fully separate the units from one another.When I turned a 2-story single family into a duplex a few years ago, we ended up having to pour a cement floor between the spaces.

I do think bad data is better than no data, with regards to the Zestimate...My 'give them the benefit of the doubt' in their algorithm is that perhaps us folks that are interested enough to actually click on the 'Edit Facts' button (us) do correlate to being relevant to adjusting value - vs those that don't. 

Now that I am one, I doubt anyone would ask for them. 

I doubt any state would allow withholding because of a minor fence fix.

I sincerely doubt this tenant had ever given proof before even does that exempt her now.

Just like most gurus lead with Hey I was in bankruptcy and dead broke 15 years ago but I found this system and now look at me. my story is different.. but there is no doubt it ebbs and flows depending on what and where you invest ..

You're only other option is to wait to hear from your lawyer to see if you have an legal recourse, however (this is my opinion, not legal advice) I doubt the legal answer will be "force seller to lower price".

I have two great contacts for you (Agent and Mortgage Broker) who will no doubt help you out.

You will find that each septic tank services several units per se & that each tank & field must be operational as I doubt if they are in series or allowed to operate as such.