Does a Serial Pack have to be explicitly assigned to a Variant?

-- url of the page with the problem -- : mirye.net/
-- HikaShop version -- : 3.2
-- HikaSerial version -- : 2.0
-- Joomla version -- : 3.7.5
-- Error-message(debug-mod must be tuned on) -- : none

I have a product for which there are several discount levels by variant, but they all use the same serial number methodology.

Can I assign the Serial Number Pack at the highest level of the product, then each variant 'inherit' it automatically? Or does it have to be explicitly assigned to each variant (and not the master product)?