Moralize.us alpha 
booshadows
last seen Apr 11th, 2011
have sex with your step-sister
It's right because you aren't related, however it's only right if your parents have only recently married ie you haven't lived together as siblings your entire life.
don't have a lesbian relationship with your sister ?
don't watch child porn of kids within 3 years of your own age (you are under 18)
Whether or not you consent to watching it, those children/teenagers may not have consented to making it.