Before advancement to high rank for ceremonial reasons, both Lt Philip Mountbatten's, and his son the Prince of Wales's naval careers followed a normal career path. His next son is a successful, and obviously militarily gifted, career officer whose promotions are in accordance with his service seniority. Likewise his son-in-law. His other son turned out to be unfitted for a military career, and was clearly advised of this by his superiors and persuaded to resign his commission ~ chucked out, in other words, with no concessions to his family relationships. His two grandsons have likewise advanced to their present ranks of Flight-Lieutenant and Captain by normal due process of promotion, and are normally employed in the duties concordant with their ranks and arms of the service with no concessions. All of these have initially completed the full appropriate training in the appropriate officer-cadet institution, Dartford or Sandhurst or Cranwell.
There has been none of the joining with the rank of Staff Colonel which could have happened in certain royalties at certain periods. Every commission, every promotion, has been worked for and earned; with the sole exception of the one who failed to keep up, and had to quit.