Gallic Junkers are a strange lot. They seem to be more akin to Bretonia's Privateers than actual Junkers. However they also smuggle goods and work with the unlawful factions in Gallia. This seems to be an almost brutally forward faction in that they want to make money in any way they can, and play all the sides.
As for the Gallic Junkers falling out with the regular Junkers, I never really did understand that too much. But ehh, very little has been done with the faction so its not too surprising.