Originally Posted by
Erasmus
You can add/remove infant in lap on a segment by segment basis domestically. Internationally it will require a ticket, and must be fared according to the route ticketed. If you ticketed the infant the whole way and it no-showed, it would cause problems for the infant's return internationally, but wouldn't invalidate the adult's ticket either way.
(There's nothing UA-specific about this, FWIW.)
Ticket would be domestic.
I'd be flying via O'Hare on UA, so I was specifically interested in their policy.
I've flown infant in lap on UA before, and they issue a paper boarding pass for the infant in lap for the entire trip, so I wasn't sure what happens if they issue one for segment 2 and it goes unused...