So if I send my advy character to a realm at war with the realm of my noble character, and the advy gets arrested for espionage, that's a wrong move by the person arresting my advy?
If you send your
noble character to a realm at war with the realm of your other noble character, and either one gets punished for espionage, that's a wrong move. Unless there's some actual
reason to suspect such spying.
I think your real question, though, was "are people allowed to know the family my adventurer is associated with, IC?" To which my answer would be "yes." It might take some careful research on their part, but the characters would be able to figure it out sooner or later IC.
That is a completely different question, however, from, "Should people automatically assume that an advy's family is public knowledge?"
There is a big difference between
playing within the rules and
playing well.