Law /
Rejecting an Inheritance in Poland [6]
For your kids and grandkids maybe just ignore it - the rules changed a few years ago and they can only be liable up to the value of any assets left by your brother.
For yourself, you can maybe give a pelnomocnictwo to one of your relatives to reject it on your behalf. But in any case the default state is as above - you can only be liable up to the value of any assets left over
The courts are several years behind in most civil issues - the simplest commercial registrations are often taking 6 months+ since lockdown.
Here is a useful page, up to date even if poorly written - if the amounts involved are large then contact a lawyer
dudkowiak.com/inheritance-in-poland/