in the portal it only asks for flight number, they came back to me via email requesting the flights, and they wanted the booked itinerary showing all our names and flights (to Thailand, they did not ask for any return flights in my case) btw this was the Washington DC embassy.
For my kids, I wrote a letter stating that as their mother and legal guardian they live with me. I listed my address and attached it to my proof of location/residence that I had submitted for mine. All into one pdf and then uploaded it. They didn’t ask for anything else in that area. (They did come back and ask for other additional documents, like flights and a notarized letter from my husband that the children were allowed to travel with me to Thailand)