similarities in characters are due to the program used to make them, Honey Select 2, which is a game itself with a character creation element. Also I wouldnt say that for instance Nova and for example Dalia or Penny look anything alike. Penny Dalia and Nancy are purposefully with some similarities as they family. but there are only so many morphs and changes you can make on the models before they start looking unnatural.
glad you're enjoying the games, only going up from here.