I’ve contacted to travel agency who have done a booking for us. She has informed the airline staff about our request. However, they can’t guarantee as a written evidence for you.
So another way to help you get seats with extra room leg, do you have any letter or e-mail which K. Kay’s doctor has talked about K. Kay’s symptoms on her back pain? If you could show some medical evidence to the airline at the check-in counter, they will easily assign the seats for you and K. Kay all through trip.
Please kindly inform me if you would like to have any further information or help. I will do my best to assist you.