It all depends on perspective. You're trying to figure out if you're going to let this step-mom in on your life. She's trying to figure out if her new step-kid(s) are going to be part of her life, or are just going to be there. About the only thing you may have in common at the start is trying to figure out whether what you're going to do will p!$$ off your dad [img]smile.gif[/img]
So some ground rules are in order between you.
The step-parents, are not, first off, replacements for the parent. That's one point that gets confusing. You don't suddenly replace one mom or dad with another. Instead, you get two for the price of one.
Second, getting rid of the step-parent will not bring the original parent back into the mix. Your bio-parents had a reason for splitting up, and even if it was because of the step-parent, getting the step-parent out of the mix won't bring them back together.
Third, playing the "rotten kid" card does nothing to further your cause. You may succeed in driving the step-parent away if you work hard at it, but the odds are greatest that you will get branded as a troublemaker and problem for doing so. In short, your dad will likely respect you less.
Figuring out how to work a step-parent into your life is difficult, to be sure. After all, it took you how many years to get the original parent the way you wanted them? And now to start over...? It can be frustrating, especially if you forget point 1. Just remember that the step-parent has at least twice the job ahead of him or her: in addition to incorporating a new son or daighter (or more) into their lives, they're also working on that new spouse... and since it's a package deal, they've both got to be worked on.
In any relationship, there is always you, me, and us. With your biological parents, you've had some time to build up the "us" portion. With the step-parent, that's just getting started, and both of you need to figure out where the boundaries are. Occasionally, they'll get crossed... so recognize it, acknowledge it, and move on.
Are they monsters? Nahhh.... odds are, there's a parenting board somewhere where someone's asking how to deal with stepchildren so they won't hate you. Deal with her on a straightforward basis and life will be much better. After all, in a few years, you'll be moving out and onward. She'll still be stuck with your dad