It’s my brother and 2 good friends that have some experience. the money lender would be a family member of mine lending out of their self directed IRA so they will be lenient with us.

Sound like Fund & Grow business model for $3500 for the year.  

If you create or fund an IUL instead of paying cash you can then get a loan on the IUL.

Yes i am in the Bronx market and looking into closing on a 2-4 family unit property. i am currently looking into different methods of creatively funding the deal and looking into partnerships to create capital. .

I always research the local market, compare properties, estimate expenses, and build a reserve fund.

We have found what works and repeat it as much as funds allow.

Most seller's in a sub-to don't understand the risk they are taking and most lenders have concerns over the overall portfolio quality ratings which has an impact on their cost of funds.

My IRA LLC has a name.

Doing a 75% 1st mortgage and 15% heloc or heloan would likely give you better cost of funds all around.If this is an investment property, you can do 80% cash out refi using NonQM loans such as DSCR loans, but at a higher cost/rate than if you stick with 75% loan to value. 

Another option would be working with private lenders to see if they're open to your idea should you need additional funding.