I created an fba shipment declaring 10 units but then decided to add another 10 before shipping . since there is no way to edit the contents of a shipment awaiting delivery , and since the courier collection was already booked I didnt want to cancel the shipment and start again, so I thought it would be ok ( assuming that when the extra 10 items were discovered at check in the allocated units would be increased to 20 ) but only 10 units have been allocated at check in .
is there anything I can do ? or do I just have to accept the loss and learn from my mistake .
These kinds of tactics could cause Amazon to reject your entire shipment and/or revoke you FBA privileges. You need to follow your Shipping Plans exactly as submitted.
You say your shipment is checked in. You won’t know what Amazon will do until they close the shipment, Until then, you just have to wait.