Those were not stolen - those were part of Rein🞄Hagen's setting from the start.Well considering that they outright stole House Tremere and the Order of Hermes for the World of Darkness, I guess it was inevitable that when they got the license, things would be retconned.
Lion Rampant was Rein🞄Hagen; he then took his vampire game to WWG... and included the Tremere post-accident.
Mage was built upon AM 1 being crossed into WWG StoryTeller mechanics.
People often don't realize they both originate from M. Rein🞄Hagen.
(and yes, the dot is a prentious bit of his... but I'll put it in because it's how he presents himself to the gaming public.)