General comments
Email notifications - On every order creation / modification / changes the administrators from the supplier's side will receive an email with the details and a link to approve the changes.
Order - Every order is connected to one supplier only, if you would like to order from several suppliers you will need to create orders for each of them.
Event fulfillment - At the top of the event page there are 3 numbers 5/6/7 which means 5 confirmed out of 6 booked out of 7 needed. The number at the top summarize all of the workers from all shifts including the external workers.
Needed workers per event - In case your internal shifts had the total amount of needed workers, and external workers were added, the needed amount will need to be decreased manually accordingly.