When creating merge documents, it might be desirable to include headers and footers in these documents - including text, merged fields, borders and/or images.
One page setup is used for all letters, which is selected from the first document. Microsoft Word requires the entire document to have the same margin size, header, breaks, and footers throughout, so we take the margin size, header, and footer for the first conditional document and apply it to the entire master document. As a result, all documents within a conditional merge template will have the same margin size, page breaks and header/footer content as the first conditional document. This is a limitation of the merge architecture.
In other words, if there is content in the header/footer of letters further down the list but none in the first letter, none of the letters will display this content. Likewise, if there is content in the header/footer of the first letter but not in the additional letters, it will display when they should not.
Create two different conditional mailings: one for headers/footers that contain the desired content, and one for headers/footers that do not contain the desired content
This is necessary even if the problem condition is not included in that particular merge. If the first letter contains content in the header/footer and the conditional mail merge is run without the first condition producing a letter, subsequent letters will display with the content even if they do not actually contain the content because Word pulls the margin from the first letter listed.