Call the following sub to fill your bookmarks with the data required. You can call it from your userform e.g. as follows, replacing the bookmark names and values as appropriate.
Code:
Select Case Me.ComboBoxName.ListIndex
Case 0
FillBM "Bookmarkname", "Value to put in bookmark"
FillBM "AnotherBookmarkname", "Another value to put in bookmark"
'etc
Case 1
FillBM "Bookmarkname", "Value to put in bookmark"
FillBM "AnotherBookmarkname", "Another value to put in bookmark"
'etc
'Repeat for each list index as required
End Select
Code:
Public Sub FillBM(strBMName As String, strValue As String)
Dim orng As Range
With ActiveDocument
On Error GoTo lbl_Exit
Set orng = .Bookmarks(strBMName).Range
orng.Text = strValue
orng.Bookmarks.Add strBMName
End With
lbl_Exit:
Exit Sub
End Sub