Grouping List with Parameters Problem

I have problem with creating nested list. I want to group my room with first Levels and 2nd Name parameter.
As you can see I grouped list for levels but I stucked at listing with names…
My colored my desired list…
Thank you so much.


You can use list levels on groupbykey, this would replace the list.combine approach in your example.

Thank you so much, it works pretty well.
I would like to ask you something, do you have any suggestions that I can learn more about data structures (because my solutions are often trial and error…)