Once the Multiple features add-on is installed, the Properties column displays a new menu called 'Features - multiple' :
This new menu displays the list of features as well as the list of corresponding values in a second grid :
This new menu allows you to associate multiple feature values to the selected product in just seconds!
You have the choice to tick the corresponding boxes, or to select the lines and hit the mass-association icon on the toolbar:
Conversely, you can dissociate features values by unticking the boxes or use the mass-dissociation icon:
What's more? You can for instance select all the products of a category and associate multiple feature values in just a few clicks:
Managing multiple features in bulk
Please refer to this article to manage your multiple features in bulk with Store Commander's CSV import tool.