You can assign a namespace to a Document Processor Flow at the time of resource creation or during import.
When you import a Document Processor flow (DPF) from a developer tenant to an editor tenant, assign a namespace during the import process.
If a resource exists in the editor tenant and the resource has an assigned namespace, the same namespace is used by default when you import a new version of the DPF.
Note: You cannot assign a different namespace to an existing resource.