@Julio Puentes, could it be turned into a co-working space? 

I might expect a co-author to clam up about something about someone they collaborated with.  

I don't know you'll have to write anything to the mortgage company but, assuming they're not a co-borrower on the loan, you may have to marry your fiance, only if you need to obtain another FHA insured mortgage. 

I recently just bought my first rental home (3 bed two bath,residential zoning) with a co-sign from my dad.

However, an agent or broker coming into a cooperative state to conduct business must have a co brokerage agreement in place with a licensee of that state.

Plus, I think if the DOB has it as a B3 than they are probably right and instead of a CO you may ask for a LNO-Letter of No Objection.  

As far as finding a loan that a 19 year old college student will qualify for- you pretty much need a cash loan from family/private lender or you need a co signer who has income history and decent credit.

I got permission from the seller to install a CO and smoke detector and fire extinguisher in the kitchen.

The Fed raising the interest rate is having some affect, but also on my FHA loans, I'm seeing more people needing a co-borrower to qualify.  

Ask any commercial real estate agent, as they tend to have more situations like this, they do not send an NCND, they send a co-op broker agreement and both brokers sign.