Cold Fire

I have a question about Leanne and Naesala. I'm at Part IV, Leanne and Naesala are now in the same fighting group, but they can't support each other. I thought there was a special ending for them if you get them to level A support. If so... when can the support option for the 2 of them become available, so I can get them to A level support?? Please someone fill me in!