Also, I was thinking of using a tag ["hierarchy", "parent/root/group"] for the root group and ["hierarchy", "children/subgroup"] for the subgroup. I think that would make filtering easier.
That sounds ok to me, although what happens if a group doesn't have such tag? Should it be considered a parent by default? In that case we don't need that tag for parents.
Now what if someone does a sub-sub-group?
Now what if someone does a sub-sub-group?
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