I'm sorry, but the travel agent gave INCORRECT information.
At ALL MEALS at Cinderella's Royal Table, you will find Cinderella on the first floor and will have your photos taken with her (the photo is part of the package). You will then go upstairs to eat your meal. They will bring your photos to your table during your meal.
At DINNER there are NO PRINCESSES upstairs. The Fairy Godmother and Perla (the mouse) are present, however they DO NOT go around to each table like at other character meals and take photos or sign autographs (but you can take photos of them as they dance around the room). They have a little skit/routine .....Perla dances all around and FG sings and performs some "magic". FG will make special announcements about birthdays/anniversaries.
Princesses ARE at the breakfast and lunch, and DO make the rounds of the tables for photos and autographs. Mary Poppins, though not a Princess, also sometimes appears. On rare occasion people have reported that Aladdin or Prince Charming have appeared at breakfast, but they are quite rare. They are not able to tell you who will appear on any given day....in fact most people report that even when you check in that day for your reservation, they won't spoil the surprise and tell you who is upstairs.
Since I'm sure your friend will be confused by getting conflicting information between the travel agent and this board.....she should call 407-WDW-DINE and talk to them so that they can confirm that FG and Perla are the only characters present upstairs during DINNER.
If your friend is looking for a dinner meal with Princesses, they are at Princess Storybook at the Akershus Restaurant in Epcot's Norway. The Princesses appear at THIS restaurant for breakfast, lunch and dinner. There is one Princess in the lobby for photos (part of the package) and then 3 or 4 different Princesses making the rounds for photos and autographs at the your table.
You can also see Cinderella, Prince Charming and the step sisters at Cinderella's Gala Feast at 1900 Park Fare Restaurant in the Grand Floridian for dinner. (Breakfast is called Supercalifragilistic breakfast and features Alice, Mad Hatter and Mary Poppins, but no Princesses).
These 3 restaurants are the only places that Princesses make appearances at meals. All the Princesses can be found for meet/greet at various locations in the park, though you will need to check that day with a Cast Member about who will be appearing and what times. While they can appear in many places, sometimes just walking around the parks, they typically hang out in these places:
Toontown in Magic Kingdom usually has a couple of Princesses (and this is a very cool meet/greet because they take you into a room to meet the Princesses so it's a little more private than out on the sidewalk with the rest of the line behind you). The lines here tend to get rather long, so it's best to go early or be prepared to wait. The room you go into has all the Princesses in it, but you meet them separately, they each have their own little section or the room.
Belle in her blue dress, either alone, or occasionally with The Beast in France (Epcot).
Belle (usually in her blue gown, but at the hard ticket parties she may be in her Yellow Gown) has a Storytime with Belle which is a regularly scheduled event in Magic Kingdom. It's just to the side of the castle, ask a CM to point it out. She retells her story and brings a few audience members onstage to wear a costume item and be her friends (Mrs. Potts, Chip, etc).
Aurora (Sleeping Beauty) can be found in France (Epcot). Aurora also makes a brief appearance at a Tea Party at the Grand Floridian, but this is a fee event.
Jasmine can be found in Morocco (Epcot) often with Aladdin, and sometimes with the Genie. Jasmine can also be found in Adventureland in Magic Kingdom.
Snow White can be found in Germany....sometimes with Dopey. The rest of the Seven Dwarves rarely appear, usually for special events or holidays only.
Ariel has her own Grotto in Magic Kingdom. It is also a more "private" meet and greet as the line waits outside while you go into the grotto to talk with her. She is always in her Mermaid form in the Grotto. The only place to see her with legs is at the Princess meals (she's in a green gown).
Cinderella sometimes will be in Fantsyland.
That's all I can think of, though there may be other places to find them in the parks....ask the CMs that morning as they'll have the schedule or can call and ask.