Multi-image packages limited to folders
I am an equestrian photographer and I sell photos of horses/riders from events. If you look at a gallery, a rider may have several "rounds" at an event which I name/label sequentially (401-1, 401-2...).
Instaproofs multi-image basically says "any image at all anywhere in the entire Instaproofs account (across any galleries) may be purchased as part of a multi-image package".
But for the way I want to charge my customers, I want multi-image products that are not only limited to a single gallery, but limited to a single folder. So, as an example, if someone wants to buy a "retouch package", they should only be allowed to choose up to 6 images from a single named/labeled folder (eg: 401-1), as opposed to right now where they could purchase 3 images from folder 401-1 and 3 images from folder 401-2.
Because there's no way to really clearly say "this is how you can buy" I often have to issue refunds or ask for more money from buyers.