Using a combobox without overwriting existing data

I have a worksheet containing employee information (i.e. name, manager, department, etc.). I also have a userform that will be used to make changes to the employee information. The userform has three comboboxes and, when activated, the userform is populated with the existing data in the worksheet.

Here is the problem - I need to have the existing worksheet data populate (as it does now) but also have the combobox choices available in the event that one of the 'combo' fields need to be changed. How do I keep the existing worksheet data AND keep the functionality of the combobox?

Does this make sense? I feel like I'm rambling!