So, in other posts on this forum, parents have commented that the service academy application does ask if the applicant has a sibling or parent that attended the academy. I don't know if this is true. But if it is - at least Admissions does see this fact.
And for what it is worth, the published profile of the 2018 graduating class at the USAFA included 11% legacies (54 siblings of graduates and 58 sons or daughters of graduates).
See:
https://www.usafa.edu/the-breakdown-the-stats-on-usafas-class-of-2018/
And the published profile of the USAFA Class of 2026 includes:
54 sons and 31 daughters of service academy graduates, 6.6 percent of the class.
Forty-one men and 21 women are sons and daughters of U.S. Air Force Academy graduates.
Both parents of six men and two women in the Class of 2026 attended the Academy.
Six men and three women are the children of U.S. Military Academy graduates.
Six men and five women are the children of U.S. Naval Academy graduates.
One cadet is the son of a U.S. Coast Guard Academy graduate and two cadets are the daughters of U.S. Merchant Marine Academy graduates.
On Acceptance Day 2022 cadets received their fourth-class shoulder boards, signifying their acceptance into the Cadet Wing.
www.usafa.edu