How can I group collection by row group?

[trolikua]

Hi there!
First of all, I want to say thanks to everybody who works on the fantastic package!
And now my question.
I have an XLSX file, where some rows are grouped. Ideally, I want to get the same structure on the backend after the file importing, but I can't find any mentions about working with group levels and so on.
My work file looks similar to this:

My goal is to have information about parents for every nested row.
Can anybody help me?

Thanks.