Your net gain is your net sale, minus your adjust cost basis.

And each former LP (now a tenant in common) can do a 1031 exchange on their portion. 

When the smoke clears after a sale, everything falls to the buyer's responsibility.  

Currently we are seeing STR owners posting for sale due to reduction in prices they can get per night and the vacancy rate increasing. 

It means that you, as the purchaser, cannot close on the purchase of the property until (subject to the terms of the contract) the seller identifies a new asset to acquire with the proceeds of the sale. 

Lenders often include a portion of the cash flow in the investment property as income to you personally to offset the DTI. 

I need funds (but only for the buyout portion of the deal, and she's agreed to certain percentages).

From an email I received from FF:New year, new rental goals! There’s never been a better time to step into the booming mid-term rental market. Since you’ve shown interest in listing your property with Furnished Finder...

@Kezia Edmonson Yes, you can use a 1031 exchange to defer taxes on the sale of your single-family investment property when purchasing a multifamily property, but only the portion used as investment (the three rented units) qualifies.

So if we were to assume the loan, we need to take a second mortgage to cover the equity portion of the loan.