You may want to train nana during daytime first. Do not let her wear diapers. Then you tell her if she feels like urinating, she must tell you. When you feel like urinating too, you let her hear by saying you want to pee & let her see you sitting on the toilet bowl. I did this to Alexx but twice she pee on her underwear then after that I often ask her, "do you want to pee?, do you want to pee? until finally she made it.
Nightime, I let her pee before going to sleep. Then midnight I will carry her to the toilet. Now she only pee before sleep then pee in the morning when she wakes up.