Hi Pina,
Thank you for the suggestion.
It seems to be nice but I don’t know what use-cases that would need to list the same note in multiple notebooks.
As I answered here for the similar feature request, notebooks are basically designed to behave like folders.
So, I’m afraid to say that the feature is not going to be planned at the moment.
BTW, I’m planning some improvements on how notebooks behave as I wrote in the next roadmap (draft) so please check it out!