How to keep only useful thumbnails?

Hi David,

Congratulations for your great plugin!

There's only one little thing I'd like to change about it to make it perfect for me.

If you look at the provided link, when I select "Custom kit" in variations, the two images attached to this variation appear in thumbnails: this is perfect.

But when I select "STD kit" or "Reprint", there's only one image attached. Therefore, the unique thumbnail is useless and I would like to hide it.

Is there a way to do it easily?

Thanks a lot in advance for your help and all the best.

Tommy

The page I need help with: [log in to see the link]