Hi everyone !

I try to have the success "I believe I can fly" but I d'ont understand exactly how to have it. I have to kill 30 chlidren, ok, understood. But how do I have to do it ? Finish the game as a Martyr, then as a Succubus and kill 30 children with her ? Finish the game as a Martyr, then as a Succubus and once again in Succubus and kill 30 children with that last save ? Or finish the game as a Martyr, then as a Succubus (kill 15 children) and again as a Succubus and kill again 15 children to have 30 ?

I have already all the others success on this game.

Sorry if my question is a little weird but I'm completly lost.