Real Estate / Property on my wife's name - Inheritance in Poland [3]

My late wife's father had a property in South West Poland (Opole District). When he died his third wife continued to live there.He had two daughters and a son - all from his first wife. The property seemed to belong to the three children and the surviving wife (previous wives deceased). The three children decided to put their share of the property in my wifes's name. Not sure of reason for this. The surviving wife died 20 years ago with no children but other family members - brother nephews. nieces. They did not show any interest in the property and its upkeep was maintained by my sister-in-law (resident in Germany). and myself. In English law my wife's estate passed solely to me by virtue of a will. I now wish to pass the property to my sister-in-law so that she can dispose of it. It does not have any significant estate value due to the location and condition. What is necessary under Polish inheritance law to achieve this? What is the position regarding the technical interest in the property of family of the third wife.

JC