How to merge a Business Partner to Both Customer and Vendor Roles in SAP S/4HANA?

[RahamanEmal]

Dear SAP S/4HANA Experts,

In the SAP ERP system, transactions FLBPD1, FLBPD2, FLBPC1, and FLBPC2 are used to create business partners from customer or vendor master data and to establish the appropriate links.

In SAP S/4HANA, I manually created a business partner using transaction BP and assigned the Customer role. I would now like to associate this same business partner with a Vendor that belongs to the same legal or economic entity.

At present, I am attempting to add the Vendor role (FLVN00) to the existing business partner. However, I encounter an error message indicating an incompatible account group:
“You cannot create a vendor with grouping KOST.”

My question is as follows:
Is it necessary to define a vendor account group in Customizing that mirrors the existing customer account group KOST—using the same name and number range—and to link this vendor account group to the business partner role FLVN00? (Path: SAP Customizing Implementation Guide → Cross-Application Components → Master Data Synchronization → Customer/Vendor Integration → Business Partner Settings → Settings for Vendor Integration → Define BP Role for Direction Vendor to BP)

Or is there a different recommended approach to achieve this integration correctly?

Kind regards,
Emal Rahman