sales employee need to be showed in COPA

Hi experts,

Sales employee is created without HR module. In SPRO, partner function ER is assigned to sold to party AG. In COPA, sales employee fail to show.

Request: sales employee need to be showed in COPA

Question 1: Is it correct to use ER? If not, which one should I use?

Question 2: How to meet the request?

Plz help. Many thanks.