Can I track items in Modifiers?

[Asash]

How can I track my drinks in a meal modifier with a burger?

I have modifiers enabled, so when somebody's ordering a burger they can either get just the burger, or a meal deal with drinks and fries. I also have drinks being sold separately, with 'Track Stock' enabled. I want the coke bottle inventory to deduct the bottle from the inventory when the 'Meal Deal' option is selected - right now its only being deducted when the drink bottle is ordered separately. 

Anybody done this? Thanks in advance!