There's also a lot of instances where the overlap is inevitable. All ALS's movements are made in Glashuette and all JLC's movements are made in Le Sentier, but for all the other brands (VC, Cartier, Panerai, IWC, Piaget, etc) they have their movements made to varying degrees by ValFleurier or each other.
If it goes through ValFleurier, though, it will be made along a specific architecture that will be easily traceable.
Piaget, for instance, makes their own movements, but also sources movements from JLC and Cartier via ValFleurier. Piaget then turns around and sends other movements to Cartier. Cartier makes some of their own movements but also gets some movements from ValFleurier.
To mapit all out would require a lot of red string.