I'm searching a long time for a solution to add authors to products.
Then I found the table "va_authors" and the row "author_id" in the "va_items"-Table.
But there ist no way to specify an author.
Then I found a file called admin/admin_authors.php, which is not linked in the static-Tables-Menu. There you can create authors. But still there is no way to add these authors to products.
It ist very important to me (and sure to much others), that this is solved.
 
And what about adding more than 1 author to a product?

Hi,
 
You can assign a Sales for the products. In V3.6 You can find this option if edit the product, and search for select user above the Supplyer selector.