I think i get what you're going for now, and indeed it may be tricky, there isn't much for 'easy' dynamic widget property dialogues, I think Sean wrote a recent blog article on developing custom widget property dialogues (it's also in documentation) but from what i've seen it's pretty in depth. You would have to make your own custom UI so when you select an employee, it can do a lookup and present the right UI to select the features.
Another option you could possibly do, is just select the employee itself, and then your widget could show certain fields based on the employee type (user wouldn't select it though), or you could try to create some sort of "Display profile" that the user selects on the widget and that display profile grabs and displays differently depending on type type of employee selected...