When attending a Royal function, don't just assume you can sit with your friends at the table, and in the first free space you can find. Somebody will have spent days carefully organizing who sits where, with who, and why. Specifically, that's the entire job description of the Royal Master of Ceremonies.
The order of precedence is of vital importance when putting such a seating plan together, but it isn't the only factor that's taken into account. The age, interests and first language of guests is also taken into account, with a view to ensuring that no guest is left isolated by being unable to communicate with those around them, or by being sat with people who they have nothing in common with. Last minute cancellations by guests are usually solved by drafting in another Royal from somewhere, or the Master of Ceremonies spending a late night completely rethinking their plan for the evening and, presumably, their life choices.