Yep.
All members of your party in the same room must have the same tickets and same dining plan on the package.
Dining plans, once added, are issued for every night of your stay and cannot be shortened (as in, just the first four nights out of seven). No one booked in the room can 'opt out' of the dining plan for that room. If it's
DDP for one, it's DDP for all and for all of your nights.
The tickets thing is more flexible, since you can buy one- or two-day base tickets (depending on the promo you are using) for everyone and then upgrade to parkhoppers, non-expiration, etc individually. It is possible for everyone in a party to end up with different ticket variations, but the original booked ticket option must be the same for everyone in the same room.
One thing to consider may be, if you're looking at having too much food with the plan, to buy the QSDP and then pay out of pocket for a TS or two during your stay and just explore counter-service dining the rest of the time. Another way to 'burn' credits is to book signature dining or dinner shows like Hoop-de-doo which take 2 TS credits per person.