I purchased this 5 Unit building for $140,000, and I used the equity from one of my SFH rentals to come up with the Down Payment!

That's not super thorough or safe for either of you. 5) Use a third party loan servicer to make your monthly payment collections easier as well as the end of year tax documents needed.

Without tying up all my cash, what avenues should I pursue to cover the $72,400 cash payment I will need to make the deal happen on top of taking over the current owners loan?

Even with rates where they're at lenders require you to have a certain ratio on the payment of rent vs mortgage.

You're probably buying at higher rates, but just run the numbers, see what you can afford, and compare potential monthly payments to what you could get in rent.

The payment is $2,196 with my current insurance.

1) make the payment directly from my HELOC account2) transfer the money from HELOC to business checking account, and then make the payment from my business checking account.

We use the RHAWA lease agreement, if you are not a member of that organization or WLA, I would recommend you sign up.In the RHAWA lease agreement (not Seattle specific), it states that security deposit can be used all purposes including unpaid rent, damage, cleaning, late payment, utilities, keys and other charges.It is never a bad idea to pay for an hour of an attorney's time to go over any of these concerns and then you can be confident you are following the law.

Protect that down payment money.  

Unfortunate situation but learned our lesson with up front rent payments!