Is it permissible for me to add my brother's date produce to my own in order to market it governmentally without the knowledge of the competent authorities?

It is not permissible to take a brother's dates to give to the government, as it is a personal production. As long as the state markets dates only to specific project owners, this constitutes deception, falsehood, and unlawful appropriation of wealth. It is obligatory to cooperate with the government in its beneficial endeavors for them to succeed, and circumvention will lead to the cancellation of those endeavors.