If someone with a normal last name finds our they have a dragonmark through an ancestor long forgotten, do they change their name to d'(House) or do they keep it d'(Last name)? The houses will usually take in "foundlings" – people who develop a dragonmark due to a blood connection – in which case they'd typically take the house name. If the foundling doesn't join the house, they aren't entitled to the name.
— Keith Baker🔜DragonCon (@HellcowKeith) July 21, 2019