My group dining expectations is this:
-If you order a group type appetizer (cheese sticks, calamari, fried mushrooms) that comes in pieces then you offer some to your dining companions.
-If you are dining with a group and only one person orders an appetizer but you and other's don't then when you are offered part of the app you decline. If the person who ordered the app stops eating it and it's just sitting there, it is fine to say "you know I think I will try one". You can also accept if the person who orders it says "No really, take some. I just really wanted some calamari but if I eat all of this I won't be able to eat my main course."
-If you are dining with just one person and you want an appetizer you discuss options with the your dining companion. Actually, I beleive in any group dining instance you should ask your companions if they plan to order an appetizer because if everyone says no, then you should ask if they are ok with you ordering one since your request will delay them getting their main course at most restaurants.
-If you order an appetizer that is obviously meant for one person such as a cup of soup, I see no need to offer to the other tablemates.
I've taught my kids the same rules so would be very suprised if they ordered cheese sticks and didn't offer some to others. My kids were also swimmers and I know how hungry an after practice teen or tween is, but that didn't give them the right to forget what I consider to be their etiquette rules. I would have done similar to the mom and picked up the cheese basket and offered to the other dining companions because I would have thought my DD's hunger had taken over her ability to be gracious.
On the dessert discussion I've also seen instances where one person orders a dessert while the rest of the table turns it down but still the waiter brings multiple forks or spoons. I always find this preseumtious of the waiter.
What would you do with someone who does not follow your rules? I would be really upset if you imposed them on me...especially "sharing" food.
I take exception to the bolded as well. If you are dining with a group, discuss ordering appetizers as you stated later on. However, there is nothing wrong in ordering an appetizer to eat yourself or to share with your dining companion only. In my experience it does not delay getting the main course by that much and usually people are busy talking anyway.
As to it being rude to eat when others don't have their food, that is not always true. If you get an appetizer or a starter--such as soup or salad that come with some meals and not with others--it is not rude to eat those when they come out and are served to you. Not everyone's meal comes with a starter, for example a sandwich platter probably won't but a dinner entree probably will.
Also, if you are with a very large group, there is nothing wrong with starting to eat your meal while it is still hot. Most often someone will say, "don't wait on the rest of the food, eat while your meal is hot." I hate to see people sit and wait until everyone is served and by then some meals have cooled. We were out with a group of 18 last weekend at a very busy restaurant. There was a time lapse of about 4-5 minutes between the first and last meals arriving and we encouraged the others to start and not wait. Didn't bother me in the least.