Faction Heir or Family Member

[jlefranc]

How can I make a faction's Heir show his last name? Also if another person is of the same direct line as that of the reigning King, they also do not show their last name i.e. "Capet" for France. Thanks

[Caesar Clivus]

You can't make heirs show the last name.

[The Source]

england family members in the early era are known to have not showing the last name