The buyer had someone else pay more to build it than the value added, they had someone else do the associated work, they can get home purchase financing, they do not need to wait months for the ADU to be constructed.  

number of tax parcels, number of physical buildings?

@Garrett Mathis PMC software is mostly focused on tracking leases, tenant payments and then various other building data.

I'm in Livonia / Canton area and I haven't attended any Washtenaw County or Ann Arbor REIA events but I do attend the Oakland County REAI meeting in Troy as well as the Michigan REIA meetings in Troy and they are super helpful and if you sign up to get their emails you can check the topics in advance to make sure it's worth the trip for that meeting.They usually have really good speakers. 

Start building a list of local  lenders (private and traditional)  contractors, handymen, realtors, wholesalers,  syndicators,..... 

Build your design around the area.You wouldn't want to do a Miami beach theme at a high mountain cabin.

. 🏡🏢 Rather than tell you what features I want to build, I would love to hear from more investors like you about what challenges you’re facing, what’s not a pain point and what tools you have that are useful, what tools aren’t — so that I can build something would actually be helpful to you!

The interest paid on a HELOC may be deductible if you used the funds to "buy, build, or substantially improve" the first home. 

Leverage equity in other properties, build a team, and connect with local Houston investors.Good luck!

This was sold to a local person who had no intention of building there, but just want to use the golf course and other amenities.There are many property owners who are trying to sell lots in Eagle Rock, and many who are letting their property go for tax sales.