We have started our DONE3 booked with AA RTW Desk.
I received yet another itinerary change which allows us to 'rebook once'.
Previously, I have not had need to change what was offered.

What are the rebooking options?

Specifically, DFW-SFO has changed enough to give the rebooking option.
Can we ask for something like DFW-YUL instead (assuming we have an available surface segment to get to MIA)?

Currently, we have BKK-HKG-DPS-KUL-NRT-HNL-ANC-LAX-SJO-DFW-SFO-MIA-DOH-AMM-CAI remaining on the ticket.

Recognizing that we'll have to pay a change fee(s), can we change DFW-SFO-MIA to DFW-YUL-MIA?
And can we just ask to dump AMM-CAI from the ticket (to have an extra segment if needed)?