I guess they are the same Taxes so it makes it easier.

The tax paid from your lending proceeds should be the equivalent of your tax rate I would think.

Build your database and clients.

Definitely a question for a tax attorney/accountant, especially with the dollar amounts involved. 

@Ross DerouenBigger Pockets is a great place to find an accountant specializing in real estate taxation.A good real estate accountant can save you thousands of dollars by leveraging entity selection and formation, tax deductions, cost segregations, bonus depreciation and tax planning.I recommend finding an accountant specializing in real estate taxation, business taxation, financial planning and tax planning.Consider working with your accountant remotely to expand your options.I would also recommend looking for an accountant willing to work with you throughout the year.

There was a news reporter at the sale and they interviewed the high bidder, who admitted that they had not seen the property, but were certain that they would be building their family home there. 

if it is unsecured loan that is the consequence, you lose they entire thing. as far as tax write off, sorry but none.

No matter where you settle upon, your idea to build really comes down to your goals.

If not, they may consider building the ADU and down-sizing into it and renting out the main house.

Is just the fact that no garage could be a no go for some buyers enough to build it even if it only raises the value by the actual cost?