Yo, John -
Gosh, I haven't traveled with a tribe myself - LOL! - but no, I don't think you'll have an issue. That said, it would be great to hear from the folks who have. Hopefully, some of them will chime in so just sit tight for the moment, OK?
I saw your Colosseum question and took a run at it. That darn site has made SO many changes over the past couple of years that I'm only half confident that my info is current/correct for about 5 minutes!
Arrival night? It'll take you a bit of time to get to your accommodation, checked in and settled so I'd limit evening activity to dinner and a lovely walk by some of Rome's landmarks, assuming the weather cooperates. I don't know what you'll have for a guidebook but most include self-guided walks, as does Rick's. He also has some free audio tours you could download to your own devices. Mom and Dad could give a listen and pass along the more interesting points to the kids orally.
https://www.ricksteves.com/watch-read-listen/audio/audio-tours/italy