Newbie questions, I hope this is an OK place to post this.

Some time back I had a trip booked with Delta, that went BOS - CDG (on Air France), CDG - AMS (on Air France), AMS - BOM (on KLM). The day before the flight, I was notified by Air France that the BOS - CDG flight's schedule had changed. It would now arrive at CDG too late for me to catch the flight to AMS. The notification came about 30 hours before the flight departure time. The flight had been booked through the travel agency we use at work (FCM).

In my nervous haste, I did not call FCM to try to get rebooked, which I think (?) would have been the right thing to do since the ticket was booked through them. Instead I called Delta, since the tickets were issued on Delta (and not AF nor KLM). The agent I talked to was very pleasant, and said he'd try to rebook me, but asked me repeatedly if I was sure I wanted to rebook and whether I had any car, hotel, or cruise reservations also attached to the same itinerary. "If I take control of the ticket now, your travel agency will not be able to make changes to the hotels, cars, etc. Normally we only take control of the ticket 24 hours or closer to the flight", was roughly what he said. I told him to go ahead, and he booked me on an earlier flight (on Delta) BOS - AMS, allowing me to catch the AMS - BOM flight with plenty of time. It was good that he did, as it turned out that there were hardly any other seats available for the day of travel and if I'd delayed calling I might have been out of luck entirely.

So it worked out well for me, but curiosity leads me to ask, what exactly is entailed by "control" of a ticket? I had the vague idea it had to do with when the airline or the airport gate agents can start assigning seats for a flight. But what the agent said to me suggests that it extends beyond flights and includes things like car rentals and such if they were booked together? Also the agent implied that those would all be blocked for the travel agency if he took control of the ticket, but clearly he was unable to tell himself whether or not there were car or hotel reservations attached to the booking. So what would have happened if I had had a car rental, for example - would it have gone into a black hole where nobody, not the travel agency, nor the airline, nor the car rental company would be able to see it? And if that's the case, how can an airline get control of a ticket 24 hours before the flight - what happens to the non-flight portions of the booking? Or was the agent simply making stuff up for me? :-)

What is the advice for such situations in the future - call the travel agency and hope they have access to other seats that might be available for rebooking, or call the airline (who may access to more seats?? or not?), and how does the 24-hour cut-off play into all this?

Minor question - when Air France notified me that the BOS - CDG flight would be delayed, should they not have tried to rebook me anyway? I think with the revised schedule I had about 35 minutes to catch the CDG-AMS flight. It's surprising that this did not trigger any automatic consideration to rebook since it seems too little time to transit clearing EU immigration, etc., at CDG. Even on the phone, the agent had to look at the revised schedule for a bit before admitting that it "seemed too tight" - is there not some standard criterion for minimum connection times that would be flagged by their software?