Obviously with an email. DD1's birthday is next month, so over the course of the last few weeks I have had my DF and DFIL etc asking what they could get her. I have amassed a small list of things I know she would love and things she has specified and saved it on my Amazon wishlist.
So AIBU to send them an email along the lines of Hi, this is divergentdd1 birthday wishlist - please feel free to choose anything from here as she would love any of it. Much love etc
And that way we won't (hopefully) get double presents like the last two years