To create routes that can be used on multiple parts:
Click Production then click Manufacturing Route Maintenance.
This brings up a new screen, where an existing route can be viewed, edited or by pressing F4, a new one is created. The P shows that this is the preferred route.
In the other parts column, a cross indicates that there are no other parts associated with the route, a tick means that there are. It is possible to F5 on that column to see other parts and amend them.