Also, the existing loan is already seasoned, and a good portion of the interest has been paid. 

So dad gifts a portion of a down payment "many years ago" and doesn't contribute to a single mortgage payment, and now the siblings want 1/3 each? 

Feel free to reach out and I would be happy to help with any portion of the process and I work with all of these lenders on a consistent basis. 

They need an extra $56k to to cover a portion of purchase price and closing costs, monthly holding costs, and the first payment to the contractors(required by first lien lender).

Let's say that you use a portion of your $36k Roth as a down payment on a rental property purchase.

If there is a trust in place, you could look at changing the beneficiary and portions there of.

Any advice on the process besides the stamp portion is also welcome.

A large portion of investors in the US are known as “buy and hold” investors.

So a portion (the term portion) of your permanent policy payment does not get invested.

Two other considerations here. 1) you said OO meaning selling within the next 3 years will generate a tax free 'gain' for the owner occupied portion of your property, so that could influence your decision process. 2) If you refi you will have fees to pay, so the question is are those fees worth it.