I think you can rename the items to do it, but I'm not sure. So there's two options you can go with here.
1: renaming the items (this might not work) just /rename while holding the item and add whatever you want to name them afterwards.
2: Use item tags. While holding the item, do /i tag set <name of tag> <value> for these last two, it doesn't really matter what you put, but having a different value or name of tag for each item will disallow them from stacking (I think)
If neither of these work, then I'm sorry I couldn't help further. If you want, you can message me and I can further investigate how to do it.