I know if we were taking out a loan this would not be possible as down payments for investment properties cannot be gifted, I'm not sure what the rules for all-cash purchases are.Since I manage our other investment properties in the area (all under my name), I don't want to put this new property in her name as it will create additional hassle of signing a new contract with our PM, creating new accounts with the utility companies, etc.Thanks in advance for the help!

In addition to the 6 apartment homes, there are three empty lots being sold with it. 

Given your goals in getting into multifamily, it may be worth considering the opportunity cost of selling now & potentially losing out on any additional appreciation or whether you'd be able to find anything in the multi space anytime soon.

I currently own 50% of a 45 unit mobile home park in South Daytona and I have an additional 4 unit property under a cash contract.

In addition, if they have had the dog there for a long time they may be able to argue that the landlord lost the right to enforce the no pets clause.

These are all great suggestions, I would add do not overlook the power of referrals and building a network in addition to online marketing.

Additionally, I have a decent amount of flexibility at this job and experience large periods of downtime on a daily/weekly basis. 

Just an additional avenue. 

I've looked over many of the older posts in the MN forums so I have seen some names thrown around, but just thought I'd see if you had any additional thoughts.

We're after a multi-family unit to purchase so we can rent the other apartments.By day, I'm an AI researcher but looking to build some additional cash flow through rentals.