Q: Is it possible to merge watermarks onto google doc?
R: No you cannot add a watermark to a doc.  If you can add the image in the corner and don’t need the text to overlay over the image, then you can just have the image on the doc somewhere.  If you need something like “Draft” you can put in the heading/title. Or create a table with a narrow column on left or right with an image of the watermark that runs along the side of the page.