Which assignment must be avoided when setting up a cross-company purchasing organization?

When setting up a cross-company purchasing organization, it's essential to ensure that the purchasing organization is not directly assigned to a single company code. This is because a cross-company purchasing organization is designed to consolidate purchasing processes across multiple company codes, allowing for unified procurement strategies, better negotiation leverage, and the possibility of aggregated purchasing volumes. Assigning a purchasing organization to a specific company code would limit its functionality and defeat the purpose of having a cross-company approach, leading to inefficiencies and complications in managing intercompany transactions.

The other options represent valid assignments within the framework of a cross-company purchasing setup. For example, having a purchasing group associated with a plant makes sense in terms of aligning procurement responsibilities to specific operational areas. Similarly, a purchasing organization can indeed manage relationships with multiple suppliers, and it is common for a plant to be linked to its respective company code to facilitate appropriate reporting and financial transactions. Therefore, avoiding the assignment of a purchasing organization directly to a single company code is crucial for leveraging the full potential of a cross-company purchasing organization.