We are talking about inheriting a property and also savings....
Basically, in this case, it's up to the court to use common sense. You need a lawyer to push them in that direction, but the money for the maintenance of the property will come out of the settlement before it's distributed by the court.
What you're seeing here is the classic zawiść. They want more than they're getting, so they're willing to delay it for a long time to make sure that you get as little as possible, even if they lose themselves. It's very, very normal in these situations with Poles.