These three children are minor characters in the Koudelka mangaverse. They reside in London, and are children of the prostitutes that Joshua knew before moving away. Nene is certainly Kitty's daughter (in volume 1, she refers to Kitty as "Mom" while being lifted), but Timmy and Becky can only be guessed at who their mother is. These three aren't of great importance, except for comedic relief.