Switching from FNSKU to UPC for next Amazon shipment — is it possible?

Hey guys,

I have a quick question regarding Amazon FBA labeling.

For my current inventory, I sent everything to Amazon using FNSKU labels (manufacturer barcode covered). Now I’m preparing a new batch, but this time the units only have a UPC barcode on them.

What I’m trying to understand is:

• Can I switch from using FNSKU to UPC for my next shipment? • Is it allowed to send the same product using UPC instead of FNSKU going forward? 

And if the answer is yes:

• Will the units I already have in stock at Amazon (sent with FNSKU) be affected in any way if I switch to UPC for the next shipment? 

Would really appreciate if anyone who’s done this can share how it works or if there are any risks/issues I should be aware of.

Thanks