All we know is that the feature exists for some users. If you want to see if you're one of the lucky ones, open an existing wish list you have on Amazon. If there is a button underneath the title that says "Invite," you have access to the feature.

Clicking on it brings up a link that you can send to others to add to your wish list.

It's not clear what percentage of Amazon's users have this feature turned on, nor do we have a time frame for when (or even if) it will be rolled out to the larger public. But what we do know is that Amazon is testing the capability for this feature, and we can hope it will be expanded soon.