Quick question regarding open-jaws and 2-4-1 vouchers. I have an open jaw booking LHR-MEX // SCL-LHR. I have already completed the LHR-MEX segment. The booking is with one of the "new" vouchers that allow booking into I class.

Can I

1. change the inbound to another departure points as long as MEX-XXX is shorter than the shortest segment on the trip (LHR-MEX in this case), for example EZE-LHR?
2. change the inbound to another destination, e.g. SCL-MAD or SCL-LHR-EDI?
3. change both the departure and destination point, i.e. the trip would effectively be a double open jaw, e.g. EZE-MAD or GRU-LHR-CPH?

Thanks a lot in advance.