If you need to get up, ask first.
Please, thank you and waiting for everyone are the classic table manners for kids. Turning them into a quest makes them fun to practise instead of a list of rules.
Kalmdix announces the mission as a playful quest at the start of the meal, then lets the children talk about whatever they like. It works on one habit over five meals; on the fifth, the mission is a secret. Kalmdix never says who did or didn't do it: the results appear after the meal.