Paperwhite-non amazon download files not available in family library

Hello ,

I have copied non amazon downloaded files in az3 format to kindle paperwhite, I can see it in my library All / Downloaded,

however I am trying to setup kids profile by going to

settings -> household &family library and selecting a child dropdown and library, I cannot see the copied files , all I can see are downloaded from Amazon, need help in sorting this so I can assign books to profiles.

I also tried mobi format it is the same.

Thankyou.