Since this thread has 206 views (though no responses), I thought at least somebody might be interested in an update. Spent nearly two hours on the phone with the BA call center yesterday; spoke with two supervisors and two different agents (in one call; see "long story short" below).

1) BA was able to retain our SCL-JFK leg in spite of a need for ticket reissue (see below) and no availability if we were to rebook from scratch. Curiously, BA was unable to find availability on a slightly better routing (SCL-JFK nonstop vs. SCL-LIM-JFK "direct"), in spite of QF, AA, and LA seeing availability (I started a new thread on this topic).

2) AEP-MDZ is on LAN Argentina but LAN Argentina / LAN Chile constitute one partner for purposes of BA award (I thought this would be the case).

3) BA charged us the "online" price for a ticket reissue ($50/passenger) as opposed to the call center price ($70/passenger). They would have changed the dates for free over the phone because we could not change the dates on BA.com (our itinerary included the stopover). From BA's point of view, they charged us $50 to cancel our existing itinerary and no fee to book the new one (i.e., the online prices -- which they "routinely" give to call-center booked itineraries with a stopover, because stopovers on partner awards cannot be booked on BA.com).

LONG STORY SHORT: BA didn't really give us any extra help on account of the earthquake. HOWEVER it was implied in my discussions with both supervisor and agent that, while date/time changes are FREE online and cost $70 at the call center, change fees are customarily waived if for some reason your itinerary can't be changed online (e.g., because it has a stopover). NOTE: first agent did NOT know that online date/time changes were free. She thought they were $50 (this is why it required two supervisors).

LONG STORY SHORTER: If you want to do something to your booking that BA will not let you do online, the call center should only charge you the on-line price.