Best approach for party wall prone to damp.

Current renovating a 1900s terrace, solid walls. Currently they have gypsum plasterboard on and I can see there is damp behind where the screws are on a party wall, and know the neighbour had damp at the bottoms of their side of the wall. A damp survey informed us it was likely because their air vents were blocked off. The neighbour told us they want to keep them shut to stop bees.

I know very little about plastering, so excuse my ignorance, but I am not sure how to best handle this.Does anyone have any guidance? I guess I won’t know what the true situation is like until after the plasterboard comes off, ? But unsure how to plan when hiring contractors.