You can exchange diapers at Costco.
If you need to exchange the diapers for another size or brand at Costco you can do so with or without the receipt as long as you are a Costco Member.
Just bring the diapers back to Costco and tell them that you want to exchange the diapers and they will gladly exchange the diapers for you.
Costco's 100% satisfaction guarantee allows customers to return diapers anytime if they are unsatisfied.
Receive a full refund or exchange when you show proof of purchase such as a receipt or provide your membership number if you have lost the receipt.
Also most stores will allow you to exchange unopened and undamaged diapers for a different size.
Just take the pack back to the store and ask customer service if you can exchange them for another size.
Walmart Stores will also exchange diapers for another size as well.
If you are satisfied with the product but need a different size, then Walmart allows you to exchange diapers (including Parents Choice, Pampers, Huggies, Luvs, etc.) for a similar or the same product within 90 days.
Costco will accept returns without a receipt thanks to their risk-free 100% Satisfaction Guarantee.
Since all purchases made at Costco are done with a membership card, Costco can easily look back at past purchases on their database, so no receipt is necessary.