Min, max and multiMax on a modifier group.

I have a modifier group that offers a choice of 5 types of beverages and the client must choose any combination of 6 to accompany their meal for 6. They can choose 6 of the same if they want, or 3 of this, 3 of that, etc.

I tried a min of 6, a max of 6 and a multiMax of 6. No error or warning was raised but it doesn't work. You can only pick 1 of each beverage (there are no + or - buttons), and since there are only 5 choices, the min of 6 cannot be respected and so the meal for 6 cannot be ordered.

How can I make the modifier group behave as described in the first paragraph?