I want to set a field value (choice column) based on if other fields are selected.  I have a few date fields and a few checkboxes that, if selected, I want them to automatically populate the choice column (it's the issue status).  How do I keep from one from overwriting the other?

For instance, I have the choice column automatically default to a certain status (pending), then when one group works on it and enters a date in a certain field, the status should change (scheduled).  Then, another group will work on it and update either a different date or check a box (completed date or a choice of checkboxes why it was unable to complete).

My problem is, how do I make sure that the status doesn't revert back to a scheduled status?