I want to do a one-time (no update) MailMerge, into the existing document.
The permanent "locking" almost works with

Set myFields = ActiveDocument.Fields ' or ActiveDocument.MailMerge.Fields
?!?
For Each fn in myFields
If fn.type = wdFieldMergeField Then
fn.Unlink
End If
Next fn

Problem: the Fields in the header are not affected (which is good for page
numbers...but for that I have the " If fn.type = ..." ).

-- How can I unlink Mergefields in headers?

I just can't find the ActiveDocument.Fields equivalent for headers.