You also have couple of configuration options handy to tweak the component as you wish:
A little component to manage related products in bulk easily for the current branch of VirtueMart.
You can filter for Category and manufacturer to select the target products, then select from the list the products you want to manage in the first step. In the second step you can select the related products, and you can save the obtained combination to be reused.
On the third and last step you can select what to happen with the combinations you created in the previous steps: