https://www.theverge.com/2018/7/27/17621224/amazon-wish-lists-collaborative

After years of customers pleading for the feature, Amazon has started to roll out the ability to build lists with your friends and family, as spotted by Android Police. But don’t get too excited just yet — Amazon confirmed in an email to The Verge that the option hasn’t been rolled out to all users, and it doesn’t specified how quickly this will arrive to everyone. Previously, Amazon has had an option for users to share their lists with people, but has never allowed users to add items to a collaborative one unless they were using the Wedding Registry. The feature is sure to be useful for party planning, roommates, holidays, birthdays — basically any event where multiple people need to buy stuff together.

To check and see if you can invite your friends and family to collab on gift lists, navigate to any list that you already have set up. If you see a bubble underneath the list’s title that says “Invite,” you’re free to start sending links to friends that allow them to edit it.