In an upcoming DONE5 itinerary, we have scheduled

EZE - GRU BA 246 Jan 21
GRU - LHR BA 246 Jan 23

and are wondering the ramifications of not taking the 2-day stopover in GRU, but rather flying directly EZE - LHR on BA 246.

Clearly if we want the extra stop somewhere else, making the itinerary changes that eliminate GRU and adds another city would attract a $125 change fee. My question, however, assumes that we don't need an extra stop enroute elsewhere in the itinerary.

Our understanding is that a date change alone (i.e. changing the first segment, EZE - GRU, to be Jan 23) should attract no change fee. Do the experts on this board think that a change that results in

EZE - GRU BA 246 Jan 23
GRU - LHR BA 246 Jan 23

would be permitted, and done for free? If so, are there any known dangers in making this change, any GRU-specific issues (i.e. the routing would require us to pass through GRU immigration and potentially miss the continuing flight)?

Thanks in advance for your knowledge!

Only question is whether changing from a stop to a transit will be classified as a reissue.

If anything it should save taxes - a transit generally being cheaper than a stop

I am advised by a reliable AA RTW agent that non-AA flight date changes now require a reissue; however, there is no charge for the re-issue. (I cannot see where this would result in a $125 change fee, unless you insisted upon a tax recalculation due to no stopover.)

Look at this thread (and in particular post 20) Unnecessary reissue demanded by Qantas?. That thread is a tranist to a stop over, but some commments valid
Who issued the ticket ?

Issued by AA --- or more precisely, by a TA on AA stock (at my request).

I believe that you should be able to make this change for no charge. In principle you could get the tax back by reissuing the ticket but that is a change so the $125 fee is unlikely to be less than the tax recovered.

If you keep it as 2 coupons and don't ask for repricing to get extra taxes back then it is a date change. Stopovers can be transits but the reverse isn't okay (transits can't be stopovers).