Originally Posted by
cloudybw
1) Can I call to add MMM-NNN, making NNN a connecion and effectively travelling from MMM to AAA in the previous case?
Yes.
In fact, you can call in, and book your original ideal itinerary AAA-MMM-AAA-ZZZ. Erroring out on the website does not mean it is not bookable. I'd suggest find the individual flights for that and give it to the agent so you can avoid the 'NNN' city in general.
Originally Posted by
cloudybw
2) If 1) is not possible, can I call to change NNN-AAA to another date with connection? The date of NNN-AAA I booked without connection is not ideal.
You could also do this, however, you would *likely* be charged a change fee if the carriers change between the original NNN-AAA and the new one.