You should receive 600 euros each (including the baby), that's all that will be offered. I would suggest starting with a quick read of the first few posts at
http://www.flyertalk.com/forum/briti...61-2004-a.html . In cases like this (with a substantial night stop on a mechanical delay), BA will usually pay without objection.
P.S. Welcome to FT and the BAEC forum, we're glad you've gained a lot of information from this forum and good luck in your pursuit of Gold. We wish you were here under better circumstances, but we're glad to have you here and look forward to your future posts.