I’m not sure if I fully understand, did you preorder before boarding or inflight?
What should happen is that the complementary service items such as water and pretzels are handed out first, after which any preordered items should be delivered.
The crew should switch off/suspend the BOB option to all customers so that nobody can order anything.
The crew should then take the trolley through the cabin, front to back to allow customers to buy anything they wish.
After returning to the galley the crew should then reinstate the BOB option so that customers can make any extra purchases.