Besides my List with DocumentSets I have a separate List with all the single Documents from those Sets, and I want to have a column with the Name of the particular DocumentSet.

Is this possible?

Is this a duplicate list?

You could create a view on the orriginal list that shows all the documents without folders. Since document sets are shown without folders that should allow you the same behaviour as the duplicate list.

This may or may not help your current problem but it would simplify your design.

Thanks for your reply!

Yes, thats exactly what I did, and it worked out fine!

But now im searching for how to tag that documents with the document set name!