If there is a schedule change in your itinerary you *may* be able to sneak in a change if it is not too major. Some agents want to help and will sneak it in knowing that since they can change the booking due to sched change they are not likely to be taken to task making another minor change at the same time. Don't ask AP if there are sched changes, investigate this on your own and try to disguise the rebooking as due to the sced change. Long shot but you never know!