Sourcing Rules/Blanket Purchase Agreements

 I am in the process of trying to establish "new" blanket purchase agreement for inventory items that have an exisiting sourcing rule for another supplier.  This supplier is listed as an Approved Supplier for several (1000 +or-) items. How do I go about creating 10 new blanket purchase orders for all inventory items for multiple suppliers? 

My problem has been that I have been creating blanket purchase agreements and checking the appropiate "update exisiting sourcing rules" and the sourcing rule is still set to the exisiting supplier.  How do you override that supplier rule so that it will start auto releasing to the new supplier.