(I am not a parent)
When departing T4 earlier this month, as I was waiting on the bus to be shipped off to a distant outpost of the Raj (aka Stand Victor) I saw a 767 being pushed back and a chap picking up two push chairs (not the 3x3) from the bottom of the late bag drop 'helter-skelter' and putting them into his van and driving off. Could only conclude that they were delivered to the wrong machine, or did not make it in time for despatch.
Ten days later ... at JFK, already boarded and waiting for push. I see ANOTHER pair of push chairs being picked up off the late bag drop and loaded into a company van!
Hint: Don't take your baby's push chair with you but check it in at the start! It might be a pain not to have it airside whilst waiting but a lot worse not to have it land side at arrivals! Especially, if you hagve just done, say, 14 hours to HKG.