Is the grandmother's testimony sufficient to prove that my father's brother is entitled to half of the deceased grandfather's capital, in the absence of any material evidence?

The testimony of a single woman is not sufficient to prove ownership of property, based on the verse: "And bring to witness two witnesses from among your men. And if there are not two men [available], then a man and two women." However, if the heirs confirm the claim of the deceased's brother, then there is no objection, and they must do so if they know he is truthful. It is not permissible for them to conceal his right, based on the verse: "And do not conceal testimony, for whoever conceals it - his heart is sinful." And whoever among the heirs acknowledges the validity of his claim, such as a grandmother who testifies for him, then she must give him his right from her share of the inheritance.