This scenario is entirely possible and I've done stuff like this before with seller finance (SF) properties I've purchased and then refinanced later.That said, if you have the downpayment now, why not just use conventional financing now?

I currently own a duplex in Indiana and bought it using a conventional investment loan.

Bradley, yes it's conventional but again... most lenders will hit you with the 20-25% DP.

Assuming it is conventional, the max seller concession can only be 3% for less than 10% down payment 6% seller concession 10%-25% down payment 9% seller concession for more than 25% down payment@Albert Bui @Carlos Valencia

Conventional financing is far superior to FHA when it comes to being a Non Occupying CoBorrower. 

Did the Trojan Horse have a wooden dick?

I was told that if you purchase a property using a conventional loan (mortgage in your name), that within a month or so after you purchase the property, you can use a Quick Claim Deed or Warranty Deed to transfer the name on the Deed of the property to your LLC.

Conventional 15 year fixed Lessons learned?

The average build cost is nearly identical but the lower price range nets out 308 builds in ten years vs 303 with conventional algorithms. 

Once down payment savings reaches ~$60k use $40k-$50k as a 20% down payment on a conventional sfr, and use recouped primary residence closing costs for the sfr closing costs, remaining $10k-$20k goes into the sfr reserves12.