Hi,
without spending words on this requirement and if it is a good idea or not, the request could be satisfied with a little customization of the Auto Group plugin. It should be analyzed more in detail, but you could use the same function triggered when the user field changes to get the current field value and create a group to assign the user to. And the field should be configured as "read only" to avoid further changes (with creation of new groups).

But just AS-IS is not possible because is out-of-scope of Auto Group main feature (that is, assign an user to an EXISTING group).

Kind regards,
Luigi

Hi,
the smarter way could be created but requires a little plugin customization. The current rule allows you to specify the group (or groups) to assign for each field value (or values). A rule is always needed, the plugin do not know what you want to do.

In your case the rule is your custom way to manage this association, you need to take the field value and use it as group name to assign to. It's easy, but requires a little change in the plugin code. It is not difficult if you know a little PHP programming, and is much better then mantain and compare 8000 or more lines.

Kind regards,
Luigi