Depends Better EXP gives more control you can choose when a random event happens. Radioactive changes more of the game add a new suppression and a gameplay way to remove Flaws for a short time to see events play out when Billy does not have a flaw and a girl goes through their Nympho or Obsessive scene. While both give cheats Radio is more cheat then Better EXP.
Basically, get the mind control power, then use it on them to Suppress Family Ties. You can also give them a mental illness with Psychoschism or whatever but this has notable downsides to it such as causing energy drain at night or forcing events that drain health and take up a time slot. If you go the mental illness route Billy gets raped unless he has Mind Control (and therefore incest flaw) so you really should get that anyway. For the sister you also need Sympathetic Link.
Allie, Chelsea and Stephanie require the Ephebophilia flaw, with Stephanie requiring Incest and Suppression of Familial Ties.
Use Passion3D's version - for link see his post a few posts up. I had the "matrix" error with original build too. With Passion3D's version + RadioActive 0.39.01-RA2 saves load without any error. (Looks like new version of RenPy introduces some slight incompatibility - once you start playing a version compiled with newest compiler, you can't downgrade[?])
Did you pick her as a starting perk? If you did not pick her, she won't be in your game.
No Billy still can feel love. Wild Oats is there for the girls he loves while yes it only makes them "loyal" Billy would not do it if he felt nothing for them other then a place to put his cock
For future reference, Radioactive includes Defense League Hints. Pressing Shift+F12 would have provided you with a hint on how to proceed with both of Derek's paths.
Didn't the dev say the shot made him incapable of feeling love anymore? That's pretty direct confirmation if you ask me. iirc he used to have a thing for Sandra but now he just wants sex.
