I've never negotiated such a deal so I'm seeking any advise. 

If they're 10 year tenants, you might have an opportunity to increase rents as well! 

We had our second home rented out before the closing.At this point and after reading numerous books on real estate, I realized that although we had reached our goal of owning a rental, our finances were completely vertical and I need to spread out to increase cash flow and reduce the impact of a vacant property.In January 2016, I started data basing different markets across the USA.

You can google "We Buy Houses in LI," call bandit signs if you see them, go on Craigslist and seek out ads who are looking for properties, or even post an ad stating you'd like to work with investors to bring them deals and locate investors that way. 

Also, any potential pay increases, windfalls, inheritances, etc are not included.

However, be careful you properly forecast for increases in the property taxes.  

So take your estimate and increase it by 10 or 20%.You don't want to invest in thin deals especially with an HML lender.

Looking for fellow investors seeking to network in Southern California and connect with deals

Large luxury apartment complexes have been built over the years around the area meaning the rental business is increasing.

Your cash flow and equity increases become bargaining chips for your Applications to keep borrowing, to buy MORE bargain cash-flowing investments!