The family member has held the buildings for decades and managed on his own, but he is 80 years old with health declining and cannot properly manage them anymore.

If by saying I am "too off center" you mean equipped and conditioned by those with 1st hand perspectives, yes I am. 

New Orleans, LAthere's Tulane university and 2 large health systems owning several hospitals across the city (Ochsner and LCMC). 

For less active income (some would refer to as "passive income"), without a job, you're going to need to get a dscr loan but you'll also need to have a balance sheet to take the property down meaning you're probably going to need to partner.I would also try to see if you can improve your health issues before you start this new venture.

@Andrew Foster some decent advice here, but also some feedback from those who really don't have enough info to support their perspective.Many DIY investors price repairs on materials only and forget about labor as they do their own work.We're a PMC in Metro Detroit, but here's how our process would work:1) MoveOut Video & Pics used to create Scope Of Work (SOW)2) SOW broken down into Priority Categories:- Health & Safety- Government Required (municipality/S8 inspection requirements)- Property Preservation- Marketing Impact / Tenant Retention- Miscellaneous3) Bids obtained if we feel work will exceed Owner Approval Threshold4) Bid sent & discussed with owner to, "redline to their budget"5) Work begins once owner approves & funds6) Completion video/pics providedOf course, while this is going on our Marketing Dept would be doing a rental analysis & ad, and discussing with owner.

They can gaslight you, but that is just a distraction.They actually sell wipes to detect pot residue on walls, but I am not sure if they work and I would not spend the time or energy in engaging in establishing "proof" - you'll put up walls and they'll just dig more tunnels.Instead, I would:Contact their case worker ASAP, cite the behavior as a lease violation with her, and state that in addition to it being a breach of lease, it is creating health concerns for your family. 

Comps are useful but they are always backward-looking and reflect past market conditions.

A properly installed radon mitigation system with post‑test results under typical safety thresholds doesn’t devalue a property; if anything, it reduces a future buyer’s objection by turning a health risk into a solved, documented feature.

( difficulty reselling the unit, and it has a small percentage risk on your health)I would like to know if the value of the condo will decrease overtime and your thoughts about the situation.

Without knowing the total picture (goals, income needs, tax bracket, heirs, health and so on) the seller could put together a properly structured long term lease option, that should do the trick.