Q: If I ordering small box item should I ask the supplier to paste my upc code on each of my product? Must I ask them PP bag outside the box then with amazon code outside?
A: If you are using FBA, you have to apply FNSKU label on top of the packaging (including bubble wrap or any kind of wrap/cover/polybag). And, to avoid the fulfillment center staff from getting confused between the barcodes (UPC or FNSKU) they should scan, please cover any UPC or manufacturer barcodes with a blank label or FNSKU label.
For your reference, here are some resources relating to your situation:
Question answered by Sharline.
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