General cautionary thoughts for posters and lurkers, don't do anything irreversible with the 529, in case your DS or DD leaves the SA, voluntarily or involuntarily, or until you are confident he/she is going to stick it out.
We observed one situation with a USNA sponsor daughter, rather upsetting to see. DD1 was a promising athlete and scholar, parents scrimped and saved to send her to expensive boarding prep school with prominent team in her sport. Mom took a second job. DD1 is recruited by and accepts USNA appointment. Parents divert DD1 529 to one-year younger DD2 to help fund expensive college out of state. DD2 is not a stand-out scholar or athlete, stayed home to attend public HS. DD1 decides to leave USNA after 1 year. Parents say DD1 got her share of the family money support for her HS boarding prep, and told her she was now on her own for living arrangements and college funds. DD1 went to live with one of her boarding school coaches, got herself into a state school with various grants and athletic scholarships, got a campus job, and did it all on her own as an emancipated adult. An extreme case with sad family dynamics, but the parents were a bit too invested in the USNA thing, and DD1 was blinded by the SA low-cost option, and parental pressure, and did not attend for the right reasons.
The only takeaway here is that mids and cadets do leave SAs, for reasons voluntary and involuntary, and it could be your DD or DS, no matter how rosy things are now. Life happens.