You must assign at least one business partner to each contract account. Depending on the industry, you may also be allowed to assign several business partners to a contract account.
You can only assign additional business partners to a contract account if the respective contract account category allows you to do this.
The master data in a contract account can be divided into one part that is the same for all business partners in the contract account (in other words, cross-business partner) and into another part that is business partner-specific. You can set the business partner-specific data differently for different business partners.