Assess ALL moisture invasion issues - Longer you wait the more expensive they get so those are a repair now thing.

Once the sun sets on a warm day you can also do a thermal scan, the wet areas will show up “hotter” in the scan because the moisture in the roof system will be heated compared to the cooler evening area.

I’ll explain to him again and try to put him down gently and hope that he understands.

Make sure you understand ANY moisture invasion issues. 

I sent a gentle reminder that this was past due.

Adding a privacy fence to the property, HVAC system, and new moisture barrier.

She might not be fully aware of the risk you would be taking on so a calm, gentle explanation could do well here. 

The bigger reason I need this info is due to moisture coming over into my house via the party wall.

First off, get a knowledgable inspector to tell you what you're dealing with and suggested remedies (if needed).In general, moisture invasion is one of the bigger (i.e. more to fix) and more common items laying waste to property.WAITING TO FIX MOISTURE INVASION MAKES IT MORE EXPENSIVE>

This could be a function of the paneling and firring strips pulling moisture out of floor, or could just be a damp basement.