How much of the assets should the adopted daughter get from the will?

Ahmad Mohtram Mufti sb, I would appreciate an answer to the below question. This question is about the definition of will(wasiat) in the shareia. My brother died last year leaving behind a wife, a Son and adopted Daugther.Few clarifications before the question: 1.He did not have child from his first wife and they both adopted a girl as adopted child. This adopted child is a daughter of my other brother and she was 1-1/2 year old when adopted. 2.He had a 2nd marriage couple of years ago and from this 2nd wife ,Allah blessed him with a boy baby. 3.Before the birth of the Son, his first wife died. 4.He himself left for the next world when the Son was just two month old. 5.Our parents are alive and living with us 6.Adopted daughter is 11 years of age now It is clear from the Islamic law of inheritance that following are the heirs: 1.Wife 2.Son 3.His father 4.His Mother And it is also known that the adopted kid will not get any share from the things left by the brother. As brother was working in a company where every year one document is to be signed describing the persons who will be considered heirs to distribute the provident fund incase of employ’s death. This document was signed after the death of his first wife and before the birth of the Son from the 2nd wife. He mentioned in the document that my provident fund is distributed to my wife and the adopted kid with out describing the proportion. Question: Can we consider this document as will (wasiah) and if this is wasiah, would the adopted kid have a portion and if yes. What should be this portion? Will this portion amount should be taken out from the total asset and rest is distributed to legal heirs? I would appreciate your valued inputs to this request.