large family adr

I've seen on here that when you have two ADRs you can request adjacent or tables near eachother. When do we make this request? With the CM when we check-in or is this done prior?

I haven't been back to Disney since 2014, and so much has changed since we last went. My 60 day window opened today, and I have been so nervous about getting into the restaurants we wanted. There are 6 of us going and I wasn't sure if a larger group would make it even harder to find...

We are visiting family in Florida while visiting Disney. On a non-park day, we thought it would be nice to take our family to a chef Mickey breakfast- but with all the people, we have 12. Can I get a reservation for that many people online or should I not waste my time and just call at 7am?