Hi Teresa,
I believe you're referring to the question found
HERE. A few months ago, Disney shared some answers with the Moms Panel to Frequently Asked Questions about the Dining Plan. I just double checked this document and it very specifically says, "Dining Plan guests may not share a meal with other guests, with the exception of guests under the age of three who may share from an adult plate at no charge." So that really is the party line.
In practice, however, the situation is extremely different at a table service restaurant vs. a counter service restaurant. At a table service restaurant, you are interacting with a cast member who will see that two people are there together, eating the same food. This situation does not exist at the counter service venues.
For example, at the Cantina de san Angel at Epcot, one of the meal choices is Plato Combinacion, which consists of a chicken taco, a beef burrito, a cheese quesadilla, beans and salsa. This is a seriously large amount of food, easily enough calories for two people. I would have no hesitation about sharing this. Simply have one member of your party go up to the counter and order the meal. One dining credit will be deducted from you family's account. Then, once you're away from the counter, no one is going to know or care who actually eats the food. This will work at virtually all of the counter service restaurants, including the Flame Tree that you mentioned. Beaches and Cream is tricky because it functions as a counter service venue at breakfast and table service at lunch and dinner. At that location, I'd split a meal at breakfast, but not later in the day.
Hope this all makes sense.