How to make a Value List from a Checkbox and Text Field?

Okay, let me see if I can explain this simple and short.

I'm not brand new to Filemaker Pro but I'm not very skilled ether. I know how to create some relations, simple scripts and calculations but nothing advanced really...

I got a database with several Layouts and Tables.

1 Layout and Table, Staff Management, is for adding staff and Database users.

Then I have a layout and table, Client Management, in which I want to create 3 Value List based from the Staff Management

In the Staff Management i got a field "Name" and a Checkbox "Department".

The Checkbox gets its values from a Value List "Departments" and has the custom values: "Sales", "Marketing" and "Admin".

Now, I want 3 different dropdown lists, Sales Rep:, Marketing Rep and Admin Rep, Containing the Names from the Staff Management field "Name" depending on if the values from the Checkbox list.

Some Reps will be both Sales and Marketing, and some are both Sales and Admin, and so on, so every selection combination in the Checkbox "Department" must be considered...

How will I do this the easiest way?

Is there any other easier way to do it than with a Checkbox like I have it now?

I'm very grateful if someone could help me out here or at least point me in the right direction.

If you got any questions, please ask and I'm sorry if my English skills might prevent me a bit when it comes to describing my problem.

Thank all! Great Forum!

/Freddy Young