You have to use the Team Member Rules file to set this up.
Using Team Member Rules to Route Suppliers to Supplier Managers. You can use team member rules to make sure that the appropriate people in your company are on a supplier’s project team. For example, you can make sure that all suppliers of specific commodities include the supplier managers for those commodity categories in their project teams, and you can make sure that the supplier manager for a region is the default project owner for all suppliers in that region. Team member rules help you control which users in your company have permission to approve and manage specific sets of suppliers.
Team Member rules are set up in the worspace template under Teams tab.