This happened several years ago, but I'd be interested to get other people's opinions.
I received a lotion set (smelled it but had not used it). I planned to exchange it the next time I went to the mall. My siblings BFF stopped by, sampled the lotion, and loved it. I obviously could not return the set at this point. I was not upset. But sibling offered to buy the set from me and then gave it to BFF for BFF's bday. BFF was furious. She asked sibling if this was the same set and was furious at sibling for not buying a "real" present. A long lasting drama ensued. Was it wrong of sibling to do an "obvious" regift? Or was it not a regift at all since sibling had purchased the set?