What would be the best way to fight this increase?

@Danny N. obviously, I have no dog in the fight.

The city is wanting to tear it down, they've been fighting to not have to.

.- If they have sued others, they are more likely to be well versed in the laws, be willing to fight, and are more willing to threaten or actually take you to court.  

I'm sure there is some way we can fight back...

@WillBarnard I am a big skeptic, but I'm the type to fight my second guessing and take a risk, so I bought into the "opportunity" because of the "no money needed pitch".

so we both protect ourselves and interests, don't want to have a multi million dollar empire and fight over money not good!.

I am in the same field, and I got into real estate and think it works fairly well with education (if your job has some flexibility like mine)...I can recall spending like a hundred grueling hours fighting over half someone's deposit in the legal aid office and stalling the eviction an extra week or two on  technicalities (a noble cause for sure), but they still, of course, were evicted eventually with no money.

They rarely fight.

Essentially, you are paying for something you hope you never have to use....but if it does happen, you have multiple parties in your corner fighting off a claim, for many years if needs be, and even if the limits of one were exhausted, you have another...and the legal fees alone could be large, so nice to have the insurers footing that bill and having an interested in settling or disposing of the suit....great question, though, could you be overinsured?