As royal watchers, we are all eager to see ALL the royals. There are a few firsts today: not only the Prince and Princess of Wales, but also Princess Elisabeth of Belgium and Princess Amalia, attending a royal wedding for the first time, so it is going to be exciting for so many reasons.
I am sure the reason why there hasn't been an official announcement for the Wales' till this morning (and the royal reporter who did kinda implied it wasn't supposed to be revealed until later today) is because of security as well as not hyping it and stealing the couple's thunder.
Hopefully their attendance today will signal a new pattern in which the Prince and Prince of Wales will be the default UK representatives at overseas royal events in King Charles III's reign.