How does amazon full fill the order for pack of 1, pack of 2, pack of 3.

Does amazon take two unit to bundle for pack of 2?

Does amazon take three unit to bundle for pack of 3?

Here is what my understanding on Item Package Quantity,

"We only send the single unit: When using Item Package Quantity variation, We only send the individual product to Amazon's fulfillment centers, regardless of whether someone orders a single unit, a pack of 2, or a pack of 3.

Amazon creates the bundles: When a customer orders a pack of 2 or 3, Amazon picks the individual units from our inventory and creates the bundle itself during the fulfillment process.

Benefits of using Item Package Quantity

Saves our time and effort from pre-packaging bundles.

Reduces storage space needed for pre-made bundles."

Here is the Question

Being said that, how will I label the product using bar code for this case. Because I have 3 variations each has different FNSKU id

Note: I do have GTIIN Bar code which I got from GS1.