V.T.
M.,
I've been right where you are now!! And 15 is the worst age for girls, at least it was for my own 2. I, too have 2 step-children. We shared custody, one week on, one week off...and let's just say our parenting styles were VERY different. Mom's house was definately the "fun house" and we were mean because we made them do school work and chores. Once my stepdaughter threatened to call Child Protective Services because she felt her punishment was unfair! I dialed the phone for her and handed it to her. She just turned red in the face and stormed away. Here's what we did about school. You can do this via e-mail since you don't drive. Have the teacher send you whatever homework was assigned that day. And just flat MAKE her sit her butt down and do it, and then check it and if it's wrong or sloppy, make her do it again. We had a very difficult time with this at first and Emily rebelled big time! It was unpleasant around here for quite awhile. She just couldn't wait to get back to "fun mom's" house. The teachers usually are very understanding and helpful in these situations. We got double copies of everything. They even had her make 2 mother's day gifts.
It was an ugly year and I won't pretend that I wasn't relieved when it was time for her to go back, but today she is 24, very successful and she has and shows a lot of respect for me. They honestly do begin to see the slacker parent for what they are, but it's not an easy road. So hang in there woman and know that you're doing the right thing. The child might not see that right now, and it could take years (like it did in my case) but it really pays off in the end, and you can sleep at night knowing you did the right thing.
Another issue we had was that I was always the one discipling and that did NOT help matters at all. I finally had to get on my husband to take a more active role, but Emily knew the "orders" came from me. Still, it's only right that your husband take part in the correct upbringing of this child.
I give you lots of credit for handling all that you do. Pat yourself on the back EVERY DAY and buy yourself little treats often because you deserve it!
Best of luck
V.