Seller Sold 5 Unit Property as Fourplex Why? + FHA Refi Question

[Barrett Lund]

I apologize in advance if this is the wrong area to post this question in, I am still finding my way around the site.

Last year I found a 5 unit property that was marketed as a fourplex with "garage storage". Low and behold I view the property to see that the "garage storage" is actually a fully fledged and functional detached unit. This property also had a "shed" that wasn't utilized at all. When the bank appraised the property the sellers were adamant about not allowing access to the shed or "garage storage" and thus the appraisers didn't even look into these parts of the property, yet the appraisal still came back right at the amount that I purchased the property for. 

I know that the property would have had to been categorized as a commercial property to be sold as 5 units, but clearly the sellers could have gotten more for the property with that being the case? What would be possible reasons they sold it the way they did?

My second question is, is there any creative way I could refinance this property out of an FHA loan into a better loan that accounts for the additional property? The "shed" is now a communal washer/dryer room.