Managing stock items, when trying to do Combo's

[ReggieRich]

In testing phase of Loyverse,
We manage or can sodas by flavor, coke, sprite, orange, etc, (we don't sell many flavors, so makes it easy to manage)
so we know which flavors needs to be order when running low

I created an item for each flavor, and that goes will decreasing the stock
we now trying to set up at Combo Menu using the composite option. (1x sandwich, 1x drink, 1x snack)
However, when using this option, it only allows us to pick one of the drink flavors as item
I was thinking that the drink would have been an option to choose, once the client tell us which flavor they want, then we can select it.

I even tried using the variant option, as i saw that was allowing me to choose the flavor at check out, how ever when using this option and setting up the combo, the system still wants me pre-select which flavor (item) it want to add to the combo.

Any suggestions how i can make this happen, that i can select the drink flavor at check out in the Combo option, without having to create an Menu item for each flavor in the combo?

thanks