Do you have a good credit score?  

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

You have used home equity lines of credit to purchase investment rentals and want to know the best way to pay down the HELOCs.Between the two properties you bought, after expenses, you have $250 a month positive cashflow to use.What I like to do is pay down some principal every month with my positive cashflow.I use my extra active income from real estate commissions helping other investors to pay down the principal even more which just frees up that credit for me to use again.I know I can refinance the HELOC debt before it changes to principal and interest as it is just interest only payments as yours are.One difference is the cashflow, I have greater positive cashflow and could make the principal and interest payment in the future with the extra cashflow I already enjoy.I always get HELOCs on my income properties as well after purchasing them to pull out as much of my downpayment as possible.

THe lender is a credit union and it is a conventional low rate loan.

True re the prior poster, re this helping the seller save their credit, if you buy sub-to you will dramatically raise their FICO since the mortgage will show on-time payments.  

I finally understand that credit card payments are exempt from needing to send 1099's.

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). 

Bank Credit Line How did you add value to the deal?

Lenders desperately need/want business especially in this interest rate environment (right now, the main source of mortgage loan business in Florida is rehab financing as a result of the hurricane damages) and one way the big players differentiate themselves is by streamlining the process.

@Joe Gellenbeck Recommend you first figure out the property Class you want to invest in, THEN figure out the corresponding location to invest in.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a Class A property in Class D area, what quality of tenant will you get?