How to allow mixed attributes for one attribute only?

[adflkajdlfkajefiaudl]

Hi everone,
I am working on a site that sells t-shirts.
It has logo printing and things like that as attributes.

The minimum quantity on everything is 12. I have set all products to MIXED OFF.

What I need is for the system to allow mixed only when the "size of shirt" attribute is the only thing different.

So if someone orders 6 shirts with some color, some logo, and size Medium, and then they order 6 more with the same color, same logo and size Large, I want that to be accepted as minimum quantity of 12.

However, if another attribute other than size is the difference, I want them to be treated as MIXED OFF and require them to order 12 of each.

The reason is because we don't care if they order a different size of shirt, the screen printing setup is still the same, but if they choose a different logo or a different color for the same shirt, we want the qty of that to be the minimum qty of 12.

Has this been done already? If so, where do i get the code, and if not, does anyone have any suggestions on how to add this in? I have done a significant amount of modification to this site so I feel fairly comfortable that I could make the code changes, but I don't see any place in the code where this change could easily be made.

Thanks for any help!

[Ajeh]

This is not a feature of Zen Cart at this time ...

Mixed is for whether a Product has to be either *exactly* the same -- or -- can be Mixed attributes ...

It does not distinguish *which* mixed attributes are allowed ...