How can I reorder Nodes whose Dimension Type is Flat?

Summary:

Can Dimension Type sort Flat nodes on the view?

My customer manages a Company Master in EDM that does not have a hierarchical structure linked to an RDB and needs to change the order of records added to the 'Flat' data to meet business requirements.

The option "Reorder" cannot be enabled in the viewpoint settings for this master.

I think this is because "Use custom order" is not enabled in the hierarchy set.

However, if the Dimension Type is Flat, it is also not possible to activate "Use Custom Order" because the HierarchySet itself is not inclued in the Data Chain Objects.