17-year-old Viktor Petrov on the occasion of graduation

On the occasion of his graduation, 17-year-old Viktor Petrov received a tape recorder as a gift from his grandmother. After some time, he asked his grandmother if she would object to the exchange of the tape recorder for a video camera belonging to his friend Nesterov. The grandmother did not object and wrote in writing her consent to the transaction. The exchange took place. Victor’s father, having learned about the exchange, demanded that Nesterov return the tape recorder and take back the video camera, since he did not give his consent to the exchange. Nesterov refused, explaining that, as far as he knew, the tape recorder was presented to Viktor not by his father, but by his grandmother, who gave a written consent to the transaction. Under these circumstances, Nesterov believed that Victor did not need his father’s consent to the transaction.
Who is right in a dispute? Will the decision change if Victor's mother agrees to an exchange at the request of her grandmother?