Change vault from Private to Shared in Family Account

Hi. A second family member has just joined me in our Family Account but all she can see is those passwords which are in a Shared Vault. (I have never set up a Shared Vault, by the way, so it must have been automatically created.)  We each want to have access to all the log-ins etc we jointly have and the easiest way to do that would seem to be to change the current Private Vault to a Shared Vault, or to move the items in the Private Vault to the existing Shared Vault. Due to the large number of items in the Private Vault, moving them individually would take too long.

I have tried to follow the instructions on the website but none of them work for either Windows 11 or Android. For instance when I right-click on Private Vault I do not get the option to Manage Vault - I get the message "You can't edit this vault". I am at a loss to know how to get this sorted out. I find 1Password complicated anyway, so any help someone can offer would be greatly appreciated. Thank you.