Private Messaging Between Admin and Users Only

Hi there! I saw another request for this in your forum and then couldn't find it again!

I've been searching EVERYWHERE for a private messaging plugin like yours -- the only problem is that I do not want users on the same level to be able to communicate with each other and would only like admins to communicate with users and vice versa.

I saw another request for this and that you were working on it and wanted to follow up if that is on the horizon in the near future OR if there's a workaround/something I can put in my functions.php file for the time being -- otherwise this plugin is unusable for me.

To be clear, when a user/customer goes to "Compose" a message, I don't want them to be able to see every other customer in the database, just admin names. This would be SUCHHHH a helpful upgrade and I can't use this plugin without it, which is the main reason for purchasing a WPMU Dev membership.

Thank you!