A plain copy-link won't open a private wishlist. Invite people by email in the wishlist's Share settings instead, and give each one an access level.

If someone tells you their invite never arrived, you can send it again. In the access list, open the menu next to their pending invite and choose Resend invitation.

Viewer can look at the list and reserve from it, if you have reservations turned on, but can't edit anything. Contributor can also add wishes, but can't change or delete existing ones and can't touch the settings. Full Access can add, edit and delete wishes and manage the wishlist's settings.

Pick Viewer if you just want someone to see the list and reserve from it. The other two are for people helping you run it.

Everyone has to accept from the exact address you invited. Signing in with a different email won't work, and they'll need a Wishpicks account, though they can create one on the spot.

Invitations don't expire. They stay valid until the person accepts, or until you revoke access.

This is the same email invite flow you'd use on a public list. Visibility never grants edit rights on its own.

There's no limit on how many people can end up collaborating on one wishlist. To stop the invite form being used for spam, there is a limit on how many invitations go out in a short space of time. If you hit it, wait a few minutes and send the rest.