Help with logistics of Christmas 2018 trip

[MommyMissy]

I’m planning a trip for Next year for my family of 7 (DH, myself, and our 5 kids ages 11, 10, 8, 5, & 2 at trip time) We are currently booked at AofA from Dec 19-29. We have free dining from a bounce back offer and 7 day park hoppers. We are huge Potterheads so want to spend at least 2 days at Universal, maybe more. Originally I figured I would do a split stay, part at WDW and part at Universal but I am trying to save some money so now I’m not so sure. With the free dining does it make more sense to just Uber to universal on those days? Do our Universal days have to be consecutive? How many days would you spend at each resort? Which days would you spend at each or more importantly where would you spend Christmas Day? Any other advice you want to share with me?