We are flying from Marseilles, France to Dubrovnik, Croatia. In looking into flight options, it seems that we need to book two separate flights on two separate airlines in order to get less expensive flights--one from Marseilles to Rome and then from Rome to Dubrovnik. The difference between doing this and just looking up flights from Marseilles to Dubrovnik is several hundred dollars and almost a day's worth of travel time.
Is there some reason for this? Is there something we don't know about customs or rules that would somehow prevent us from making the flights? We would have a 4 hour layover in Rome. Please no suggestions to stay in Rome longer or see other parts of Italy--not this trip. Thanks.