The alternative is to have even more equity so that there is more free cash flow (cash income to the investor after all expenses including debt service).If you keep pulling out equity to buy more you are raising the portfolio size but you may be standing still when it comes to a sustainable income.Some folks will build a portfolio that covers itself while they continue to work full time.

However, even though it is great for quick money, the only way to make it sustainable is to create a business and hire employee's or VA's, so that the business operates independently.

I feel the need to not just create a successful and sustainable life for myself but put my children in a position to own something that generates a source of income outside of their main subjects of interest.

Property tax increases at 10% pa are not sustainable and this is going to hasten a property correction.

The property is almost self sustaining in terms of the mortgage so I only had to cover a small number with my DTI ratio.

Or, if we do see more a substantial crash in the economy (like in the disjointed from reality - mood ring for rich people stock market) we are living comfortably and below our means which will help us sustain our entire portfolio.

The property's ability to be self sustaining, measured by the DCSR, is the dominant criteria for qualification and your personal status, especially the DTI, is of far less concern.

When strangers move in together sharing the same kitchen/etc, then they do not have an established household system ("how do we live together") and they do not have the pre-established relationships to sustain them while they are establishing a household system. 

So my goal is to build enough wealth and sustainability through real estate to become financially free in the next 10 years, and quit my job.

If your rent figures are realistic and sustainable, AND if there is value appreciation likely in its location, you might be OK hanging on to it until that appreciation occurs.