Won't that just add the form as a second page? I want to add it ONTO the existing page, without increasing page count. So the second PDF is just a small block (say 6cmx4cm) and would sit ON the A4 page in the corner.
By @OEC24388674zs30
So essentially you want a mini-form that can be placed on top of any page in the PDF.
There are a couple of ways to do this. Both require advanced automation scripting.
1) Use a page template. Form cannot be positioned or scaled. It's just superimposed over a page in the PDF.
2) Turn the form page (minus fields) into a graphic and place it on the page where you want the mini-form. Try67 suggested a button image for this. I prefer to use a stamp. Stamps are easier for the user to place and size (and also use fewer XObject layers). Once placed the graphic is flattened and all the fields are created in the correct positions. I've used this one a few times. The cool bit is that its scalable. You can resize the stamp and the fields will be placed and sized to fit the form graphic.