Rahul has been using aapni for some time now. I have been trying to teach him to use it when he speaks to his teachers but have not got anywhere with that. Out of the blue though he started referring to all of us as aapni. When he is tired or excited he mixes it all up and the ensuing conversations can be really funny.
"Babu, eta dekhun!"
"Baba aapni amake Horlicks debey?"
"Diddi, tui amekey khelna diye deen."
It's rather cute though. Especially when he gets it all correct. I have always liked the sound of little children saying aap/aapni. When he calls me aapni in his own inimitable way it sounds absolutely adorable.