The suppliers register is simply a list of the companies from which you purchase supplies, services or hire equipment. Adding or deleting from this register will not affect your data that is already entered into the resources or cost vs. production registers. Adding additional suppliers will make them available from the drop down selectors in the resources and cost vs. production registers.
When you add a new record in cost vs. production that has a new supplier, they are automagically added to the supplier register.
Fig 1: Suppliers Register