PARA is designed for a folders and files approach to note taking, where a file can only be in one folder at a time.
With Supernotes, we’re not restricted to that way of thinking, and I’d advise against artificially restricting your system in the same way.
In my Input, Insights, and Output based approach to top-level notes, an individual atomic note can appear in all three top-level branches of my notes tree. For example, if I read an insight in a book then I’d track that via a parent link to the Insights note for that book under the Input branch. But the same note would also appear under one, or more, relevant topics under the top-level Insights note (e.g. Habits and Psychology). Plus, the same note could also appear under Output, if I’ve used it in a published piece of work.
This approach makes it easy to see where an idea came from, which topics it’s related to, and if I’ve already written/spoken about it. As far as I’m aware, PARA’s “single parent/folder” approach doesn’t let you do that.