A technical file can cover additional similar products from the same supplier.
For example colour variations or different sizes. You can add additional articles on the product tab with the 'Add product article button'
Within the file you need to start collecting documents that allow you to demonstrate that the product
Upload the documents that you already have to match the different requirements on the Requirements list.
This can be done at the Documents Tab
You can invite your supplier so they can upload documents also
This can be done at the Invite tab
You can group articles together if they contain:
For example these toothbrushes witt different colors or lamps with different shapes.
What you can not group is for example these indoor and outdoor lamp. They serve different purposes and your requirement list will differ.