lines fold sheets

[TECNOMODEL]

I would like to insert the lines to fold the sheet on a4 format.

the square is already there and it is ok, if change sheet size fits.
I can't find the system to properly bind the fold lines.
if I quote from the bass at the bottom right then it doesn't work anymore to change the format.

Does anyone have an indication?

 

[TECNOMODEL]

Maybe I found the way, I'd like to see if I had a twisted reasoning or interpreted well:

I assumed that the sheet is quoted from the bottom left corner. the cartilage is bound to the lower right corner.
if I quote the line of pray from the right angle when I change the sheet in a4 turns out a quota that coincides with the sheet and then by mistake.
I then created a non-parametric quota compared to the corners of the sheet, then I quotated the line fold from the left corner and entered the expression "sheet-210".

That's how it works.

I've been thinking right. Did I take it by mistake?

 

[callaghan]

I did so, I inserted it in the edge, drawing the fold lines to 210x297
of course in the a4 format will not be seen, or better they will coincide with the outer edge