Illegitimate kids that are declared as legitimate kids by family even though no bloods as done and was requested by the legitimate to the metal industry.

This is a big concern. The deceased who is the father to the kids has his legitimate kids however there is one child that we the mother suspect it is not his. The father of the children has told all his legitimate kids that the child is not his. Even though he had married the mother of the illegitimate child she was pregnant at the time and he later found out the child was conceived from another married man. He later said that he cannot do bloods on the illegitimate child because the woman won't allow him. However the company whom the dad works for is owned by his brother and so his brother ***ner of company) had instructed his daughter and his secretary to declare the childrens name and fill out the forms on behalf of us. To my amazement they declare the illegimate child on the forms as daughter. I notified the metal industry of that child however the owner of the business does not want to talk and declare if it is or not the deceased child he gets his secretary to talk which states it is his child. We the children would love to do bloods together with that child so we can clear the air, if it is his child she is entitled to what belongs to her dad. However the metal industry instructs the daughter of the owner of the company who is the brother of the deceased to write out an affidavit because the daughter carries the same surname as the deceased to state that it is his child which she does. My question where is the proof because one can write lies because the daughter of the owner of the company cant prove with the bloods that it his child. She is just stating that because based on her emotions that the illegitimate child is his child and is entitle to it. All the kids suspect it is not their dads child. Does not the legitimate kids have say more than than the daughter of the owner of the company who is the niece to the deceased and the owner is the brother to the deceased. Please advise how this matter can be resolved.