I'm jealous of my stepsister
Why would you be jealous of your stepsister?
She's so talented that I want to do a 'copycat'
Jealousy can be a bitter fruit. Copying her may end up doing more damage than you realize because you still won't be her. You should talk to her about your jealousy and you may realize she is envious of something about yout.
No, I will become a successful artist so that I can steal everything from her.'
You should be fostering a good relationship with your step siblings instead of being jealous of them. It's not healthy to be so jealous.