Linking background images in writer

I would like to set a background image for the first and following pages in a text document using LibreOffice version 6. This is like letter paper or designed stationary. I noticed that there is no longer a link to background images possible, as it has been in version 4 of LibreOffice. This became apparent as I used LO4-documents in LO6 and now only see a blue background and no longer the stationary design. I am dependent on this link between text document and stationary design as otherwise the individual documents including the image are too large in size (example 10KB before is now 2MB in size) and a refresh or edit of the image / stationary design is no longer possible at all.

How do I link a background image in version LibreOffice 6 with a text document first and following pages? Is there a reason why the linking of background images / design stationary is no longer possible and with inserting “normal” images in text documents it still works?