They are so adorable, Nicole.

You will have much better results trying to stack them if you put them on a non slip surface like a rubber backed rug or bathmat.

That will stop all the clenching and tensing of them trying not to slip on that slick table surface, and it will make the whole thing much easier.

Plus, if I were stacking them just to look at structure like you are at this age, I would not worry with a foot forward in the classic GSD pose. It will be much easier to get them to stand free with both rear feet stacked together.

You can only get a real picture of the pup if you can get your hands off of them. Lots easier said than done at 5 weeks I know.

They are just lovely, best of luck with them.