Add a 2nd (or more) field?

Hi,
I have been using this for ages and it is perfect, it does exactly what I need out of the box.

Lately, I have been trying to add another field to all my products, a mixture of Simple and Variable, but I can’t find anything that works properly. It is either one or the other, which doesn’t work with my export feed.

So I just had a thought! Would it be possible to add more fields to this plugin, to display in exactly the same place as it does now. They don’t need to display on the front end, just be exportable, again, just like now.

Thanks for your thoughts.