It's a tricky situation but I definitely have my reserves. 

You need to meet the DTI's and reserve requirements, by showing your income and assets.

Keep in mind a 3-4 unit FHA purchase also has reserve requirements as well. 

The rest can be put into the capital reserves.  

I tried to get a mortgage from usaa once while doing some reserve tours after being a usaa member for ten years.  

Now the deal...Financing:Potential purchase $80,000 per Duplex $16,000 down (20%)$64,000 @ 5% = $345/modouble this since there are two Duplexes$690/mo debt service for both DuplexesIncome:$26,400/yrEach unit is rented for $550/moExpenses:Taxes ~$4,000, Insurance ~ $1,600Lawn care/snow removal ~ $2,400Maint. reserves ~ $2,400Factoring a 7% vacancy (7% is conservative for the area)NOI ~ $14,152Cash Flow: $5,872$14,152 - $8,280 (debt service) = $5,872ROI: 18%Cap Rate: 8.8%COC: 40%$14,152 / $35,200 (downpayment + closing cost) = 40%3.

Does this scenario require more planning and basically start a reserve so that when we come across properties, we have funds available from outside investors?  

For instance with Fannie and Freddie (at least in the past) as the number of houses you own goes up, the amount of cash reserves you need also goes up.

https://www.hud.gov/topics/hou...if it doesn't cover your PITI and maintance-repairs-reserve and management etc.... need to keep looking. 

Now fast forward 4 years, those properties 7x'd my net worth, my net rental income is 85% *before reserves* of my W-2 take-home pay.