How to create Supplier from existing Customer

Summary:

We want to create a Supplier against an existing Supplier

Content (required):

Business Case - We sell products to our Customer. However, in some cases, we buy the sold products from the Customer as an Used Product for refurbishment purpose and reselling as refurbished product.

I get an option to enable a Customer relationship against an existing Supplier. However, I am not able to enable the vice-versa that Creating Supplier against an existing Customer.

How to achieve this ?

Code Snippet (add any code snippets that support your topic, if applicable):

No Option search the Organization in the Supplier Page