When a draft is created with a parts list and balloons, and then a part is either added or subtracted, the parts list will update, assigning new numbers. But the balloons will keep their original numbers. Is there a way to update the balloons automatically?
They will, providing that the ballon is linked to the parts list and set to display the item number.
I suspect you have one or both of these turned off.
On the balloon toolbar there are 2 icons - one shows a sort of table on it (that is link to parts list) the other I can't remember (not got edge running) but it is the one on the right of the link to parts list icon. If these are not activated you will not get updates to the balloons.
HP Z420 16GB RAM Quadro K4000 ST10 MP12 on Windows 10 Pro 64.