A gift comes from Uncle Arnold, Aunt Beatrice, Cousin Caleb and girlfriend, and Cousin Doug and girlfriend. Caleb and Doug were each sent separate invites (with guests) at separate addresses and are in their early 20s. My first instinct was to send a thank you to all c/o the home of the Aunt and Uncle, but I am now second guessing. If it makes a difference, I would bet that Caleb and Doug (like most 20yo men) had no more input on the gift choice than they will on the dress Aunt chooses to wear to the wedding. But on the other hand, I could probably write a separate thank you in less time than it took to write this post. What does Etiquette say?