Perhaps this should also apply to some other types of vassals.
It's very helpful that the game provides automatic names for new colonies when they form, and a flag too, not to mention the market name if it's an "empty" area. But the flags seem to be totally random, and the names come from places that are often unfamiliar, and I don't remember which colony is which half the time. We should be allowed to pick them, at least when the colony forms. It might also be advisable to create a standard look to the flags of certain types of vassals, to advertise what type of vassal they are, and who they belong to (example: a specific kind of border).