Originally Posted by fumje

I would think easiest for UA's ops is just leave them aboard again at end of the next flight, especially if it's the same aircraft configuration. I predict that the chance is very low of you finding an agent at EWR who is willing to take charge and spend time figuring out how to get these things back into normal circulation.

The slight hassle to your nephew of having him lug these things around the airport when returning them seems appropriate.