Game concept
Transfer
The game also links it as Transferred, Transferring.
From the game's encyclopedia
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Transfer is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Rulers can Transfer one of their Vassals to another Vassal, as long as the former is of lower rank than the latter." The game also links it as Transferred and Transferring. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.