Sankey diagram forcing the layers using index key

What is the problem or goal the end user is trying to solve or accomplish?

Sankey layers or steps are auto determine by Preset based on Source-Target pair. Users are looking to force the steps using index key configuration

How are they solving it currently?

Not directly possible. Have to create a dataset that has Source-Target pair that follows the steps they need. But this does not handle when there is a loop on the flow. eg: A → B → C → B

What is the recommended solution by the Customer?

Ability to use Index key to determine the steps or layers