Something seem off with this $347K offer unless this is her total compensation package value.

They know how to leverage others to compensate for their weaknesses.

We sent a letter of intent to see if the sellers agent will compensate us for the new installation out of court but they are not cooperative.

The thought of ever having to work a traditional “job” is what we fear most.The third category, where I suspect about 50% of the population reside, and which you appear to be a part of, can happily work a traditional job IF they enjoy the work, like the people they work with, have room to improve their skills and have opportunity for advancement, and IF they are being adequately compensated.  

You need what is called a "Cost Plus" agreement and you should expect to receive around 18-25% of the construction budget as your compensation. 

I just boot them out if they do things like this or aggressively raise rent on them to compensate for their behavior.

If the water bill is $100 a month, increase the price by 20% (or whatever you decide is fair) to compensate you for the time required to split and bill and to cover additional use when tenants squander the utility.

You would need to most likely consult a real estate attorney but I have heard of buyers being compensated for much less of a non disclosure issue. 

(Agents perspective) What you are asking is for an agent to do twice the work for less compensation and also to keep a seller happy.  

(b) Except for mortgage loans as defined in G.S. 53-243.01, this Article shall not apply toany party approved as a mortgagee by the Secretary of Housing and Urban Development, theFederal Housing Administration, the Veterans Administration, a National Mortgage Associationor any federal agency; nor to any party currently designated and compensated by a North Carolinalicensed insurance company as its agent to service loans it makes in this State; nor to any insurancecompany registered with and licensed by the North Carolina Insurance Commissioner; nor, withrespect to residential mortgage loans, to any residential mortgage banker or mortgage brokerlicensed pursuant to Article 19A of Chapter 53 of the General Statutes or exempt from licensurepursuant to G.S. 53-243.01(12) and G.S. 53-243.02; nor to any attorney-at-law, public accountant,or dealer registered under the North Carolina Securities Act, acting in the professional capacity forwhich such attorney-at-law, public accountant, or dealer is registered or licensed under the laws ofthe State of North Carolina.