Unique Subject-To Duplex scenario - legal ramifications?

[Aaron Duthie]

I've scoured the forums and haven't found one that addresses my unique situation below. Would love some input from a legal perspective..

Scenario: I own a full duplex. I live in unit A and rent out unit B. Each unit has its own tax ID. My FHA Mortgage covers the full duplex (unit A and B), including taxes and insurance collected in Escrow monthly.

I am considering selling Unit B Subject To to the current tenant, having them take over the unit B deed along with the whole mortgage (which covers unit A and B + all taxes/insurance).

Question: Beyond the typical Subject To sale concerns, are there any unique restrictions or ramifications I should be aware of if I move forward in this situation? 

Thanks BP Community!

[Aaron Duthie]

@Matt Devincenzo yes I believe they are two separate lots. Both have their own legal description, property ID, Geo ID...

@Wayne Brooks 1) that's the point I'm going for. They take advantage of the low interest rate on my current loan, acquire their unit at market value (current loan amount), we all avoid agent costs, and I live in my unit now cost-free. Any issues here?

@Nathan Grabau thanks for the considerations