Heh. Don't we all. What a fascinating way to approach photography. What an amazing image.
Is it possible to point your equipment so precisely that you can return to that image and continue to "shoot more data", later adding to the image?
Yes, there is a thing called "plate solving" that the imaging software has built into it where the software takes a photo, then uses triangulation with its built in database to know exactly where the scope is pointing. So, you simply plate solve the image and the software will move the scope to the exact, to the pixel coordinates that you were using on the previous outing.
Even better, the stacking software that stacks the images can use data from many different camera/telescope setups and will stack the images seamlessly, so you don't even have to use the same scope/camera to make an image.
It is extremely hard to believe what is out there now for amateur astrophotographers, both in software and hardware. The extreme precision available now days, and for comparatively little money, is awesome.