Under the current official FAQ, a spouse and unmarried children under 21 may be included in the initial application, but each family member requires an additional nonrefundable DHS processing fee and individual gift. An adult son qualifies only if he is unmarried and under 21; all family terms and amounts must be re-verified before money moves.
Family terms come from the official text, not from an intermediary
The current official FAQ says an applicant may include a spouse and unmarried children under 21 in the initial application, with an additional nonrefundable DHS processing fee and $1 million gift for each such family member. Walt's adult son fits that description only if he is unmarried and still under 21; otherwise he needs an independent route. These terms should be read again on the official site immediately before payment because the framework is new and may change.
If the son's own facts support another route, that is a separate analysis: TN requires Canadian or Mexican citizenship, a listed profession, that profession's qualification and prearranged U.S. employment; an L-1 transfer requires qualifying employment abroad and related active entities; an investor route has its own conditions. None of those is obtained through a parent's gift.