I assume you are using the back-to-back order functionality or drop ship functionality.
That functionality will let you create a PR from an SO.
If you set up sourcing rules and ASL, you can automatically convert the PR into a PO. This is called automatic sourcing. It seems you use configurator; so the Sourcing rules and ASL will have to be category based instead of item number based.
Refer to http://ns2.cat4mba.org/user-guide/purchasing-overview/overview-automatic-sourcing for setups.