Rome FCO connection United/ITA

Is this all on one round trip ticket thru United or is the Italia flight a separate ticket booking? In other words did you book your United flight then book an Italia flight? If it’s all one ticket you don’t have to worry about rechecking bags.

Did a "dummy booking" on United's site, and they do indeed sell a single ticket that is on United metal from ORD to FCO and on ITA metal from FCO to BRI. As the OP reports, the first flight has a flight ID that starts with UA (UA 970); the second flight has a flight ID that starts with AZ (AZ 1617).

UA and AZ are not in the same airline alliance and do not codeshare (meaning that UA cannot put it's own code on the ITA flight, i.e., can't make the second flight UA 9XXX).

BUT they do have an interline agreement that allows them to sell tickets on each other's flights while handling check in and baggage for each other. Typically, this means baggage will be transferred from one carrier to the other without the passenger having to do anything when the itinerary is purchased as a single ticket. It is always worth confirming this with the check-in airline.

Yes. One ticket purchased through United for the 4 flights. 2 over and 2 back to US. I’ll try to verify with United in advance that a ckecked bag will be tagged and checked through to the final destination (Bari) and avoid having to retrieve it at Rome FCO for customs check and then rechecking it on to Bari.

We've had a couple of bad issues with baggage handling. I once had to wait for our luggage in a cheap Atlanta airport motel waiting for my bag (with my car keys in it.)

And I'm certainly not going to allow any airline to check our luggage. We also carry a folding power scooter that we gate check and have it delivered to the door of the airplane at the next airport.

Thank you Dave for the information about my one single ticket purchased online (in this case via United's site) that includes a connecting flight with a non-partner/non-code share airline (ITA) through Rome. My goal is to make the connection in Rome of one hour 35 minutes with the least issues. Since my United ticket is premium economy, I can check a bag without fees. If it is checked through to the final destination (Bari) without the need to retrieve it and recheck it in Rome, then that would be my preference. I want to avoid having to retrieve and recheck. In that scenario I would not check a bag, but dragging a roll aboard through an airport connection could slow my connection process.
ITA has later flights from FCO to Bari so If I or my checked bag missed the connecting flight, I have the later flights as possibilities, even if the later flights are not my preference.
Sorry David that you've had bad experiences with luggage. I have never had delayed or lost checked bags. So maybe my luck is running out.

Airline customer service response:
United customer service looked at my booking/confirmation # and told me that my checked luggage will be checked through/ tagged at Chicago ORD to my final destination in Italy - Bari/BRI.
ITA customer service looked at my booking and said that because my ticket was purchased as a single ticket from United, I will not need to retrieve my checked luggage at the Rome FCO connecting airport when I go through immigration in Rome.
I will be diligent about watching that my bag gets a BRI tag when checking in at Chicago/ORD.