So, let’s RATIONALLY take a look at the three possible scenarios.1.

This would help save me some money to use on the house that is getting renovated and I wouldn't have any money out of my pocket up front for the duplex except when the mortgage starts.

From their point of view they're seeking three primary things:Access to capitalControl of their dealCost of capitalThey likely have a lot of the first two so the only motivation they'd have to accept your money into their deal is either the third bullet. 

The limit is "three unrelated people" and cousins are not considered related under this code.

Many Realtors will suggest purchasing a property using a FHA Loan, to reduce your out of pocket money.

Example: You have a 3-Family Building that has 3bedrooms 1bathroom on each of the three floors - 9Bedrooms 3Bathrooms Three Living Rooms Three Kitchens.

I've read Avery Carl's book and done a lot of research on (and off) Bigger Pockets.

Around this time I discovered Bigger Pockets and a bunch of real estate platforms online.

No wonder he is disliked on Bigger Pockets.  

That leaves me with 5% to come from my own pocket.