How can a requestor choose supplier site for a global blanket purchase agreement in iProcurement ?

Hello,

Lets say a Global Blanket Purchase Agreement with number 145 is created for 1000 USD for Oracle Corp with supplier site San Francisco.

However other supplier sites like New York, Boston, Chicago are available for Oracle Corp.

Now a requestor based out of New York logs into iProcurement and searches the Global Blanket Purchase Agreement 145 and adds an item from it to the cart.

Now the requestor has no choice to change the supplier site to New York from San Francisco. iProcurement automatically locks the supplier site to Sanfranciso.

Is there a way the requestor can change the supplier site to New York from San Franciso while creating the requisition.