maintaining tree structure when retrieving items from a list

it's been a while and I forget how one might maintain the branches of a tree structure when getting the items from its list - I am finding that the output is a list of consecutively numbered branches instead of the pattern that went in.

there seem to be tools that can match two different tree structures (match tree) but I wonder if that's the most direct way to do what I want.  if anyone can suggest how to preserve this structure I would really appreciate it!