cancel it closer to feb 6th it takes a few weeks before it registers that you have canceled the card...
I booked something REALLY similar as you two card holders and 4 people and we booked 2 and 2 under two itineraries just like you. one of the two people canceled the card and it took about 3 weeks before united changed the $0 baggage to $25 for one if the bookings. but in our case 2 checked bags is enough for 4 people.