FCO airport, Rome, Italy

Gloria,
Since you're flying BA, I'm assuming you have a connection in London? What about the others - where are they flying directly from to FCO? There are different terminals for different arrivals.
This site lists the different terminals and the specifics about the flights arriving: http://www.rome.world-guides.com/airports.html
Terminal A: Domestics
Terminal B: Int. & Domestic
Terminal C: Int.
Satellites: Int.
Are you planning on taking the train to Rome? If so, you could all meet in the train station which is connected to the airport.

Thanks for your reply Steve. Yes, we are coming in fron London. Our friends are coming in via Amsterdam and Paris. Now it makes sense that they are flying in as "domestic".
Going home on Oct 25, we fly from Rome to Heathrow. But we catch our connecting flight returning to Vancouver from Gatwick. Is there a shuttle from Heathrow to Gatwick - we have a 2.5 hour window to do this.

You will not make a 2.5 connection from Heathrow to Gatwick, there is simply no way. See if your airline can rebook you on a flight out of Heathrow.

It will take minimum 60 minutes to clear customs and 60 to go between the airports, at which point you're too late.

I just Google Earth'd the route and it comes up 41.9 miles and about 51 minutes (with everything ideal). I don't see any way you would have a chance at making that layover. I don't even know why they'd allow you to book it.
You'll want to change it up and fly directly into LHR. Otherwise prepare for a night in London.

Thank you everyone who responded. This is an invaluable site. Looks like I'm going to have to do some rescheduling.

Another issue if changing airports is checked luggage unless you are doing all carryon. The last time close to 7 year ago the luggage was transfer and all we have to do was find the shuttle bus, buy the ticket, ride bus and, of course, we were the last one dropped of at HRow -- took us over two hours to make the transition. Now I understand that luggage is no longer transferred so you have to claim any checked luggage and then recheck it. I believe you will go through immigrations at the first landing and it will be strictly walk off in Rome.

Not from London, Frank, London is not in a Schengen country, so you won't go through customs until Rome.

I love how they like to post tickets with transfers between LHR and LGW. I'm going next May, and these are the cheapest (obviously!) and you pay more to not have to do this. Like you'd need a minimum of 4 hours and have to rush like all hades, and hope there's no problems. And that's if you take the Heathrow/Gatwick express trains into and out of the city, and transfer train stations on the Underground. That alone is about an hour. Take into account, going through that long line at passport control, and then re-checking your bags and going through security at the other airport, and you can see it's madness to try it. I think it's silly they sell those tickets with such tight layovers.

My experience with London and flying through is that regardless of your connection you have at least a 50/50 chance of having to go through passport control with no real explanantion as to why, or at least obvious at the time of booking.