As long as the child is a ticketed passenger there shouldn't an additional charge. I don't believe you can get a meal for lap babies. On United they have toddler meals or you can get a Happy meal, they might have one other choice, I saw these on their website this past fall. FYI we ordered the toddler meal for DD and it included raw carrots and some other item that is not really for small toddlers as it could be a choking hazzard.
Also, you can order other special meals too such as vegetarian, fruit plate, and others. I ordered the fruit plate, and did not get fruit, while the others in my party that got the regular meal had a bowl of fruit with their meal. I found this rather odd and it seemed the fruit plate that I ordered actually was a low cal or something like that meal. Wish I had known that ahead of time.
