Hi Sarah! Welcome to the Disney Parks Moms Panel!
I also have a two-year-old and I'm kind of thankful that we're not locked into buying a
Disney Dining Plan for him just yet as he is the kid who will lick a cracker and declare he's full. Of course your Disney Dining Plan entitlements are yours to spend as you wish. If you have four adults in your party at a table-service lunch, you could use four credits for four meals, or you could use two and pay out of pocket for the others or any combination works best for your family. The dining plan is not a "everyone has to use it at each meal or no one can use it", though it is smarter this way to ensure that you don't end up with leftover meals.
As far as your family, a meal for your daughter will
depend on the location. For buffets like Chef Mickey's, Family Style dining like Garden Grill, or Dinner Shows like Hoop-Dee-Doo Musical Revue, she will of course get a plate free of charge and be allowed to indulge in all-she-cares-to-enjoy. However if you're at a traditional table-service or quick-service location where each person orders their own combo meal or entree + sides, she can either share off of one persons plate, everyone can share a little of theirs with her, or you can of course pay out of pocket for the kids meal or single side option that she will eat.
I hope your whole family is getting excited for your upcoming Walt Disney World Resort vacation, Sarah! As far as
activities for your daughter, don't forget to pack a swim suit to let her play out some energy at your resort hotel pool. And make sure your entire party looks into the
Rider Switch Service! We'll see you real soon!
~Kristen