Invite users to a group

We have closed Groups where we want the Group Owners to add users from those who already have Discourse accounts. Our settings are correct and the Owner gets the Add Users popup.

When they attempt to select the users, only 1 user at a time can be added, and only by Username. A comma separated list of Usernames (or emails) is not recognized.

This looks like a bug or unimplemented feature. Is it possible to get this fixed, and ideally, allow a set of emails to be added as well?

A further enhancement would be even more welcome: Allow lists of users (by Username or email) and simply ignore those that are not valid users. Add the rest. This would be similar to how Moderators do it, with the difference that those not already users are sent an invite email to join Discourse. We would rather Group Owners not have this latter capability.

Thank you for so much development!