Automatically Default "Procurement BU" in Internal Supplier Registration

Summary:

We have multiple Procurement BUs. When users register internal suppliers, we want the "Procurement BU" field to default automatically based on the user's assignment (e.g., location or BU association).

Currently, we made the field mandatory using Sandbox, but we’re looking for a way to default the value based on user context. Is there a supported way to achieve this, or is customization required?