Down payment amount varies and more you put down the highre you will be in the queue of applicants, also down payment varies per your credit...Dodd Frank IS in play!!

It could be helpful to you (lenders will want to see lease agreements) and it is good for the family member (they actually could do a program where them paying rent increases credit). 

Current rate is 5.75 and credit scores are around 750.

Your name and credit would stay with the existing note, which you would keep paying on - ideally yourself with money you receive from the "buyer", because if they don't pay your credit is wrecked and your house is in foreclosure.If you search on here you'll see everyone and their brother looking to do Subto and it's a nightmare unless the buyer has the funds to pay the note off if/when the original lender figures out you don't occupy the property any more and are attempting to do what you want to do, since most loans are going to specify that performance.  

But somebody could use a credit card fund the immediate need and then pay it back with the policy loan fairly quickly.

Unlike banks, which offer limited loan options, brokers have access to a wide network of lenders, including niche and non-traditional financing sources.Here’s what they do:Assess your financial situation to determine your borrowing power.Compare multiple loan products to find the most favorable terms.Negotiate rates and terms with lenders on your behalf.Guide you through the application process, ensuring you meet all requirements.Example: Suppose you have a lower credit score or unconventional income sources.

Another possibility could be a home equity line of credit (HELOC), if you have sufficient equity in another propertyGood luck with your project!

Specifically, I am looking at partnering with an individual who owns securities (stock and mutual funds) having them take out a line of credit against their portfolio (SBLOC) at a low interest rate, and using that to purchase properties rather than using a mortgage.

A business line of credit through your LLC protects personal assets, builds business credit, and may allow interest deductions, but it might be harder to secure for a new LLC.

Appraisals came back awesome my credit score came back 720.