What makes it seem worse is the younger Things seem to be more of a grazer rather than eating three substantial meals a day. They are constantly eating but in small amounts. They do have breakfast, lunch and dinner and my food shopping budget can vouch for that. Thing 5 eats a hot meal at school lunch time too as well as in the evenings with his siblings.
They are all different though. The younger two are grazers. They will eat little and often..... very often. I can make them a big main meal but some of it will get left, yet half an hour later they are hungry again or will go back to what they have left. If I give them 'grazing' portions spread out over time it all gets eaten.