Fiddle stroker,

Here is some examples of controling one text field with another, one
checkbox with another and one dropdown with another.  You could of
course adapt a necessary:

Sub ROE()
Dim oFFld As FormFields
Set oFFld = ActiveDocument.FormFields
On Error Resume Next
ActiveDocument.Unprotect
On Error GoTo 0
If oFFld("Text1").Result = "Hello" Then
 oFFld("Text2").Result = "World"
Else
 oFFld("Text2").Result = " "
End If
If oFFld("Check1").CheckBox.Value = True Then
 oFFld("Check2").CheckBox.Value = True
Else
 oFFld("Check2").CheckBox.Value = False
End If
Select Case oFFld("DropDown1").Result
 Case "A"
   oFFld("DropDown2").Result = "Apples"
 Case "B"
   oFFld("DropDown2").Result = "Broomsticks"
 Case Else
   'Do nothing
End Select
ActiveDocument.Protect wdAllowOnlyFormFields, NoReset:=True
End Sub

To test, enter two text fields, two check boxes and two dropdowns in a
document.  Enter A and B as options in the first dropdown.

Set the ROE macor to "Run on Exit" from the first text, checkbox, and
dropdown.

HTH