Reg : ASO Hook :: iStore

Hello Experts, I understand that, if we create a new cart in iStore the user hooks "CREATE_QUOTE_PRE" and "CREATE_QUOTE_POST" will be called . If we add new item to the existing cart "UPDATE_QUOTE_PRE" and "UPDATE_QUOTE_POST" will be called. Also I understand that Every update on a cart will trigger the Update_quote_PRE and Update_quote_POST user hooks, no matter what was the operation done on the cart. This applies to quantity change as well, so it will also trigger those two user hooks. Our requirement is the change the "Requested_Date" field in the ASO_SHIPMENTS table if the quantity is changed in the cart but the user hook "UPDATE_QUOTE_PRE" is not getting triggered if I update the quantity in  the cart.