Answer
This is decided per data type and business decision. It can make sense for the ERP to lead customer master data and accounting documents, for a PIM to be responsible for approved product content and for the shop to manage baskets or customer sessions. A single system does not have to be the source for everything. It becomes dangerous when two systems may change the same information independently and no conflict rule exists.
The decision should be documented in terms the business understands: Where is a value created? Who may change it? When is it considered approved? Where is it distributed? How is a discrepancy detected? These rules matter more than the direction of an arrow in the architecture diagram. schukai can replicate data technically without blurring business ownership.
As of 3 September 2026
Further reading
Related topic: Back ends and interfaces