This plot will be tricky as he may part-own it with brothers after a death etc.
Huge red warning flag! Polish inheritance law is essentially a dysfunctional cluster fvkk and relatives are generally loathe to sign away anything they think they have a claim/right to. I wouldn't try to buy that with my worst enemy's money until the ownership issue is settled.
If your wife still has family and connections in the village that could definitely help (as some will be less likely to try to screw you over as their reputations could suffer).