Importing a pdf file to create a layer on a template I am building

I want to create a template that I can use to enter the info that I will then print on the pre printed checks I get from my bank. They come 3 to a page and are 8.24” wide by 8.49” high.
I am open to suggestions if there is a better way to do this.

But this is what I came up with.

I am trying to create a pdf file that will have a non printing layer (that will be a pdf scan of the page of 3 checks, and then above that I plan to put some fillable fields on which I will enter the name, amount of the check, etc.

Then I will put the sheet of 3 checks in the printer and print them, and only the fillable fields will be printed onto the check.

So I created a blank pdf file that is 8.24” wide by 8.49” high.

Then I imported as a layer the pdf image of the 3 checks, which is the same size.

I made the layer with the check non-printing, and the created the fill in fields as needed.

I all works fine, except that when Acrobat imports the pdf with the 3 check, it put a border of about 1.25” at the top and bottom, so the fields are no longer where I need them to be.

I cannot figure out how to fix this. I have redone it making the blank pdf page that I start with smaller, but Acrobat then reduces the check image and still has the border at top/bottom.

Any ideas, or is there a better way to do this?

Thanks