Google Product Feed - Out of Stock products

-- HikaShop version -- : 4.3.0
-- Joomla version -- : 3.9.21
-- PHP version -- : 7.1
-- Browser(s) name and version -- : Chrome

Hi. I need to exclude "Out of Stock" products from my Google Product Feed. For all my products, I use characteristics and variants. I do not use the product quantity within the "Main Option" screen - this is always set to "Unlimited". It appears this is the quantity field used by the plug-in to determine whether a product is in stock or not, not at a variant level.

Can you advise if there is a way to exclude products based on the variant quantity, rather than the quantity on the Main Options screen.

Hopefully this makes sense.

Thanks.