Adoption is the act in the Seven Kingdoms of adopting someone (mainly a child) of low or high birth into one's family.
Not many houses have practiced this act, and the only house that uses it prominently is House Harrigon. Children adopted into a house are forbidden from receiving their new families' house name or sigil. Unless the person being adopted was highborn, or possessed a house name, they are usually given a name including "New", depending on which region their adoptive family was from (e.g. lowborn children adopted into House Harrigon are given the name "Newstorm" as they are a house from the Stormlands). These names keep them apart from their adoptive families, but away from bastardry despite many low born children already being bastards.