Kay, because airlines will move a gate frequently, I would plan on meeting her at the gate of departure at a set time.

I agree with GoTravel. Also Terminal 1 security can be a zoo at times. Better to negotiate security as soon as you can and meet at the gate.

The goal is for me to find her and ensure she gets checked in. I don't want to be waiting at the gate uncertain if she has arrived at the airport, is stuck in the check-in line, going through securtiy, etc. (This is my sweet but spacey, happy-go-lucky niece.)

Are you saying Alitalia may leave from a different terminal than 1, so that wouldn't be the place to meet? I'm not counting on any specific gate assignment, just thought their international flights were all Terminal 1.

If all goes well, I will have 3 hrs connection time (rather than the usual 1 hr, again on purpose). I expect that to be enough time to find her and maybe also take my rollaboard bag on DL as far as JFK, then check it there to Rome because of the lower carryon weight on that leg.

There is a good chance your plane may not arrive at the gate it is supposed to and your flight may not leave at the gate where it is supposed to.

Murphy's Law says if you plan on meeting at the Wendy's at concourse A, they will switch your flight to leave from the furthest concourse possibly from A. Therefore, you have to pull an OJ getting through the airport and take a chance on missing your flight.

Sit flighty niece down and give her a lecture on personal responsibility.

Am I missing something--isn't the Alitalia check in counter in Terminal 1 at JFK no matter where the departure gate is? Does Alitalia use other JFK terminals for departures to Europe too?

I never count on gate assignment.