If team selling is turn on , Sales Rep field on customer records is replaced with a Sales Team subtab
and Sales rep checkbox on employee records is replaced by a Sales Role dropdown field.
In order to get the list of sales reps associated with customer. You can do the following query below:
SELECT SALES_REPS.SALES_REP_ID, SALES_REPS.FIRSTNAME, SALES_REPS.LASTNAME FROM CUSTOMER_SALES_TEAMS INNER JOIN SALES_REPS ON SALES_REPS.SALES_REP_ID = CUSTOMER_SALES_TEAMS.SALES_REP_ID INNER JOIN
CUSTOMERS ON CUSTOMERS.CUSTOMER_ID = CUSTOMER_SALES_TEAMS.CUSTOMER_ID WHERE CUSTOMERS.CUSTOMER_ID = '<internal id>';