How do I import several layers from one Illustrator file into another Illustrator file?

Hi!

I have ten Illustrator documents with appr. 100 layers in each document.

Each layer in all documents are named correctly for automatic script exporting to PNG files.

Now I want to import all layers from all ten documents into one master file. And importantly, I want to keep the exact names of each layer.

Thank you for any help on this!

David