Based on the description carnival gives on their website the 3 or 5 bottles of wine on this program are either picked up directly in the main dining room (1 at a time) or and at one of the main bars where they have easy access to wine bottles. It is not clear if it is only the mdr or also the main bars. although, the description says pick up the 5 vouchers at one of the main bars. in either case, i see now reason why you could not bring your 1 or 2 cans of soda to the MDR and mix it there yourself. I've bought shots of liquor in the main dining room and bought a can of cola and asked for an extra glass and have done similar mixing on princess and celebrity before. this will be my first time on carnival in 20 yrs.