Real Estate / ADVICE please: Rightful owner of property in Poland? Property Value? [32]

Hello,

Thank you for taking the time to read my post & Happy Holidays.

I am writing on behalf of my mother. She is Polish born now living in the US. Her mother ( now deceased ) owned an apartment in Gdańsk. Currently the apartment is occupied by a distant relative. We are hoping to find out how to go about learning rightful owner and property value. In the US we have Official State Property Appraiser Search Sites which list value and Title holder. Our distance relatives are asking us to sign some paper work. Much is still unclear. Any advice would be greatly appreciated.

Thanks again!

Jani