Definitely depends on lots of factors - I would strongly suggest learning how to do basic modeling/underwriting and projecting the cash flows out in different scenarios 

Thanks @Michael GermanoJust off Pace's promotion of another Gator method, not currently a member.One thing I'm concerned about is that I already have a line of credit, he mentioned it needs to be and LOC done through his suggested companies.

This type of financing will typically look very different and more like a traditional commercial real estate loan.That means a DSCR calculated based on a full NOI and expense load (so inclusive of vacancy loss estimates, credit loss estimates, repairs and maintenance, utilities, management fees and more – in addition to the property taxes and insurance expense that are the only expenses factored in on traditional residential style DSCR loan financing).Additionally, the DSCR minimums are generally going to be higher (typically up to 1.25x), the loan to value ratios lower (higher down payments) and underwrite more sophisticated (which makes sense considering the size and scope of the property).Many multifamily investors for properties of this size (such as more than 11 units) can syndicate capital and have more sophisticated financial and entity structures – its definitely a different world once you get up here in unit count.In Conclusion – when you are looking to invest in multifamily real estate and finance your investment – make sure you have the unit count in mind before you start shopping – the unit range can have a huge effect on your options.

I would suggest seeking out a good agent there.

I would suggest you find an accountant who is more specialized in real estate, and fast too!

A bit is missing here, I would suggest syncing up with a real estate-focused accountant to do it for you to avoid headaches and mistakes made! 

Before I continue developing, would this be a useful addition to an agent's toolbox?

Thanks for the suggestion.

The negative value with respect to the cost of building is such that it can consume years of cash flow to recover.  1) The value added by the ADU addition is often significantly less than the cost of adding the ADU.

However, I would suggest you run 3-5 properties through each model you're considering to get a feel for the pros/cons of each.