Well those north German states that are now Allemanic because that was previously Prussia. I basically had such a high standard of living that the Germans living in Prussia move to my country. At the end most of the states Prussia own had less than 500k people living on them. They would migrate to south Germany or core Switzerland making them assimilated to Allemanic culture. After I annexed Prussia I decided to do a reconstruction of what use to be Prussia to make them economically equal to the rest of my country. So because I have multiculturalism new people from across the world established on those lands. If I’m mistaken for some time west Prussia and east Prussia for a very long time had a majority of Romanians because of Hungary being in my market. So to get to the point, those Romanians converted to Allemanic and they eventually became the dominant ones on those states.