ATC down made things really difficult, there was no way to re-route my parents in time to catch any day flight between Europe and Brazil, even if they took Eurostar to Paris. I'll not even post here other option raised by BA to help them, since it's definitely not usual procedure, but there's no doubt BA likes Merry a lot. Unfortunatelly that option would not help much either.
So my parents are taking BA 247 as per original schedule, let's hope it departs on time. Grandma still in stable but grave condition, thanks for all your support.
As to Nick's help, there is no doubt he deserves all praise and I'll work on it as soon as things calm down here.
Toxa