I'm going to be a FTM in April and I'm having my baby shower in March.

I'm not picky trying to sound picky.. I'm just letting family and friends know where I'm registered (which I know hardly anyone shops from the registry) but if I get items like diapers/bottles that I plan on using a different brand of.. can I return or exchange them to anywhere like Wal-mart? I'm just worried a lot of people won't include receipts or something and I won't know where they got it from.