Upon the initial walkthrough, we identified major structural damage throughout the property.

However, I just got the Charleston County's assessment letter and it shows that the main house is taxed at the 4% and the ADU on the property is taxed at 6%, with the entire value of the home being split between the two structures. 

There was a small apartment built separate from the main house, HOA rule indicates only 1 structure, and the HOA is asking my how I plan to correct this.

But the issue is the second you get the city involved and pull permits, you typically won't be able to reuse the existing structure.

cypto tangent aside you can give sense of "equity" by selling on terms with principal and interest paydown or structure a LO that helps them build a better LTV.

How do you structure commission?

LOL.I would say do a buyout, then do your 1031.Here is an excerpt from an article I found http://www.exeter1031.com/arti..."...1031 Exchange Structural SolutionsThe partners may either sell their individual interests in the partnership, or the partnership can sell the real property and distribute the cash to the underlying partners so that each individual partner can go their separate way.

I want to structure it as an equity split. 

In searching I found a 6 bd 3 ba brick structure that looks abandoned.

As far as strength, you just dont have enough shoring on the way up the stairs maybe. a 16' stair requires more than a stringer attached at the top and bottom to be structurally sound.