My case: Users belong to a group. Depending on the selected users the group-state can be either checked (all users are within that group), unchecked (no user is in that group) or indeterminate (some are in a group).
My entire system uses checkboxes to select items, pages, and groups to move, copy or delete them. Hence, I can not use checkboxes to indicate the group-state.
What alternative input method can I use to indicate and change the group-state?
For example (wireframe): How do I add the missing three users to the group "users" without using the checkboxes since they are reserved for moving, duplicating or deleting items in the list?
Edit: Ok to make my point as simple as possible: Imagine I am not able to use checkboxes (for a technical reason or what so ever). I want to
- indicate that all, not all or no users (to the left) are inside a group
- provide functionality to change affiliation of all users (to the left) to a group at once.
A checkbox would immediately provide my requirements. But as I mentioned, checkboxes are used for an other functionality (on the entire system)