Yes, it is there but the user interface is completely garbage. You'll do better to pass notes back and forth on paper before you figure out how to efficiently send messages back and forth on this abomination of a "chat" feature. I swear it seems like whoever designed it came up with the idea in the morning and haphazardly threw it together in an hour.
If you each splurge for wifi, use your phones to chat on WhatsApp or iMessage.
Haha! Thank you for clearing that up. No wonder I can find nothing elsewhere about this "feature", apart from a post on Reddit where someone claimed that some guy had tried to start a group chat with the rest of the plane.
I'll either bring a cleft stick or we'll both cough up for Wifi. Normally I would pay up but my hubby wouldn't bother. We managed before so maybe we'll save the money for something else but I do like your suggestion of using Whatsapp. I did have the idea of running a long lead as we like to listen to the same stuff on my phone together but maybe that would be frowned upon?!