phfitz ,
you can go to the technical gallery and see a very simple example .
( already I have built three bellows so the problems is only for the panoramic format).

On the drawing there are 2 patterns for the square standards.
The size of the rear standard is 40 cm and the front one is 20 cm.
As you can see on the pic (a little bit small ) there are two red arrows to show the line of the FOLD "A" .In this case since the two patterns have the same size for a squared bellow the lines of the FOLD "A" can be joined together with no problem.
However FOLD "B" lines not of course.....

Now consider that the second pattern on the left has another size (for example 80 cm on the rear standard).The shape of it is different from the pattern "A".This is the case for the building up a panoramic 8x20 bellow.

Do the smaller pattern's folds have the same size of the bigger pattern's folds?
I suppose not ...But before to waste time, energy, money it's better make a search.
.The leather has a cost so just to get a good shape for the bellow I need the measuruments well made.
BTW Thanks for the message