Does the father's Udhiyah include his independent, married son who has not yet had children, and is it legislated for the son to offer a sacrifice before having children?

The Udhiyah (sacrificial animal) is sufficient for its owner and his household. Indeed, the Messenger of Allah, peace and blessings be upon him, sacrificed a ram and said: "O Allah, accept this from Muhammad and the family of Muhammad, and from the Ummah of Muhammad." And in the time of the Prophet, peace and blessings be upon him, a man would sacrifice a sheep on behalf of himself and his household.

If a son becomes financially independent from his father, his father's Udhiyah does not include him unless the father intends for it to do so. It is preferable for the son to offer his own Udhiyah if he is able.