I think you are putting too much of a narrative to your reasoning and that is where things fall apart. 

I don’t believe you can do a 1031 into building an ADU on land you already own, even if it wasn’t your primary.Reach out to @Dave Foster if anyone knows he would.

Are you still considering building more of a portfolio or are you happy with where you're at and you just wanna pay off the debt?

My 14 year old now makes over $100/month passive income from her % owned and my 10 year old is at like $65/month.In this process we are building their interest in real estate, teaching them the value of putting their money to work for them, and all the while growing our investment if we need it for their college money some day! 

It looks like you are doing an affordable build based on the cost but hard to say since you didnt provide info on the build itself such as square footage and finishes.

Meet fellow investors in your area and build relationships with them.

I would take them all to small claims court for the damages in your apartment.  

Quote from @William Dorrough: I currently either purchase and value add large scale multifamily properties or develop, and build ground up my issue with scaling is we have done this without brining in investors i have a great deal flow with a good track record im really looking to do more i have the capacity but have the need for more capital in one way or another  Scaling without investors can be tough, especially in multifamily.

Glad to be a part of this community. 

Face-to-face connections can quickly build trust and often lead to referrals.2.Online Groups & Forums:Utilize Facebook groups, LinkedIn communities, and other local online networks dedicated to real estate investing.