There are more options, but this is sufficient to answer your question. 

@Pat Aboukhaled I would ULS (unit lot segment) the primary house and include a clause in the call option that would prevent them acquiring the DADU.

If it is your primary residence as indicated, just sell it and skip the 1031I Persue all 3 payment options concurrently and see which pans out as your best deal.

It also identifies signer names within the documents, allowing you to uncover the owners behind the ownership entities.Currently, lenders primarily utilize the platform to monitor client and bank activity, but we're exploring options to tailor the tools for investors.

Perhaps that's the correct option if you are selling a SFH to a home owner that has unique design characteristics but not in the context of what you are facing.

I've done a lot of research and even worked on running numbers for certain options (just as an exercise), but I'm now looking forward to jumping in.

If I wasn't able to get the cash together, using a private lender would've been a good option.

You've done well with having options, now just need to decide and get on the same page. 

All things being equal, a simpler option would be to terminate the lease with a penalty of one month's rent, agreed to in writing.

If you ever want to have a discussion to explore your options or ask any questions about the concerns you mentioned, I would be happy to help!