Especially re safety. Big A will have her own seat and I've been looking at CARE harnesses, anyone used one? Or would you just use the lap belt for a tallish 4 year old? She's about 17.5kg and 110cm.
We haven't booked a seat for Li'l A but I might ring the airline to see if we can - I'm quite uncomfortable about having him on my lap in the event of an emergency, having just read an article describing infants on laps as human airbags

Wold he have to go in a car seat though or could I use a CARE harness for him too? He's 12kg so should be ok, but under 2 so would airline insist on a car seat? That would be near impossible - it would be a front facing one and we're taking the train to the airport, we couldn't carry it and our luggage too.