Vendor msssaction question

Hi,

You don't need to have a mass action. If you want to add your code in a trigger onAfterVendorCreate, just create a hikamarket plugin with the function onAfterVendorCreate and your code in that function and the plugin will be called when a vendor is created and your code will run.
What's great with the mass actions is that you can filter the elements, have different actions on them, etc without changing any code. But if you're adding your own code anyway, you can do it with just a plugin, without integration with the mass actions system.