It involves an older child (young adult?) returning to the massive starship his (her?) family has some kind of connection with. He is not initially embraced, perhaps due to some family or personal disgrace I don't remember. He is a little older than the other children on the ship and proves invaluable in some crisis and eventually earns acceptance and respect, and is allowed to stay.
The starships are massive corporate vessels, hold families, I think your right to be there is somewhat hereditary, and they appear to obey real world physics at least in part, complex navigation to destinations, lumbering maneuvers - not sure but they might also have involved rotation for artificial gravity.
I vaguely remember one incident where the main protagonist takes the younger kids to a night club - or some such location they really shouldn't be in, and begins to realise it was a mistake.
I think that in the crisis the main protagonist takes charge of the younger children and shows responsibility, keeping them safe.
This question was originally part two of a question about two novels - edited into two questions on advice from other users. I was loaned this novel over a decade ago.