How to import structured requirements

I mean... requirements are strutured in chapters / sections whatever you call it.
I'm able to import flat (= all requirements at the same level) requirements (the system is able to manage itself with ids: if the id is not filled in, it considers that the requirement is a new one, which is OK).
The question is: how to indicate that a requirement has a given parent if we don't have the id's information ?
Thanks in advance.

A workaround would be to firstly import an emply list => the system allocates ids => export the list => fill in with requirements => re-import the list.
It should work, but not very elegant.
#L.

So in the "top requirement" column, I can input the name or the id ?
#L.