It boils down to velocity of money.

Hi, what is the velocity people are seeing for for-sale apartment in NYC?

I know people who partner and increase velocity by four or five times.

Her mother died so she took some time off of work and had to travel out of state to take care of her mother for a few months which hurt her income.Her husband sells commercial insurance and has been in the industry for 30 yearsShe came to me asking me to take out an unsecured personal load on a Velocity Baking concept where she would put her future income going forward back into my revolving line of credit.   

As long as you reinvest, you can still capture velocity of money growth. 

Not sure if your family is okay with that move and what type of velocity you are trying to move at, but that always seems like the fastest way to get going.

If you want to get creative with the HELOC and try to pay off properties early, then check out velocity banking (it's not for everyone, but of course everyone can execute it).

;]Like Nick stated, even if your cashflow zeroes out in the balance, don't forget about the other return on investment quadrants from appreciation, depreciation, & tax benefits (more on this below), as well as amortization (velocity banking/rapid debt reduction strategies).If you don't have one already, I would strongly recommend finding a CPA/tax attorney (whom also invests in real estate) to help create an entity for liability protection (different schools of thought on this -- find what works best for you).With the 4-plex, one potential strategy I see would be to rent out the units to your entity which, in turn, rents out to your tenants (regardless of whether you decide to rent long term, short term, or mixed).In any case, conduct your due diligence, *negotiate*, and congratulations on a big step you've taken already!

This allows you to create velocity with your money. 

You can get a sense of the velocity of transactions by doing exactly what you explained.