They got the appraisal back and informed me that the appraisal determined the property value at a favorable valuation ( surprisingly on par with what SFRs in the area would get per SF).

You'll need to do some comp research to determine what the rents will become.

In all four of those situations, the houses were appraised with a comparative sales approach; however, the appraiser was usually able to find at least 1-2 nearby properties that were also duplexes.Rental amounts were included in the data for the appraisals, but I don't think they were used at all for determining the appraisal value. 

Can you get a realtor to pull some comps for you to help better determine your price point?

I'd suggest determining how you want to proceed.

But look at employment history, past landlord referrals and determine why the credit score may be less than stellar.

It's not magic, it takes hard work, planning and determination!

NOW trying to determine if 3/8 plywood would be strong enough IF screwed to back of 2 bye treads for added rigidity???

I'm hoping to learn and get advice on how to help my family grow their "mom & pop" portfolio and help brand it into a professional entity to increase their current profit margin while maintaining scalable processes.I'm still a newbie but am determined to learn and hopefully make some money along my journey!

The exit strategy worst case scenario determines how far under water this building really is in today's market.