I would determine what grade of location you're looking for (A,B,C) once you've figured that out.

The company that serves and blessed me over and over again is what you would call a Tax Advisor, not simply a CPA or tax preparer. 

Unfortunately having title issues is one of the reasons that sellers are sometimes willing to do seller financing simply because they know mortgage companies won't approve without proper title work and title insurance so they have to be more creative in the ways they sell but that can be risky for you as a buyer.If you do seller finance I recommend having very specific terms on HOW payments will be made and accepted and using a professional service like https://www.agecroftcapital.com/ for loan management in the case of any disputes - just my personal rec, not sponsored by BP though I do work for BP :)

Determine what you need to make to support your lifestyle that you want. 

Small Claims Court is also good, pro is you get an enforceable judgement so if anything is unclear such as damages amount that will be determined, cons are time and expense involved and once you win the big challenge is enforcing the order.  

@Maria Murphy yes correct, simply paying the debt in the owner's name to hacienda (tax office)/government first as part of the purchase at the notary and everything left to the seller.Valencia has worked quite well for us the last years and compared to Barcelona/Madrid the m2 prices are a lot lower.

But right now seems to be the absolute exception to where there simply isn't any obvious play to run with. 

I'd simply let them know that you are not going to renew their lease.

After 5 years and very little progress on the ADU valuations I suspect the ADUs simply do not have a value equal to the small unit, small count cost and never will.  

Hey Kelly,You want to determine what real estate strategy works best for you and your current financial position.