Trouble with 13yo daughter and school work

Obligatory, I'm her step-father. Her mother and I married in 2013 and they moved to my town which is about 1.5hrs from their hometown. She started 5th grade when they first moved in. Her mom/my wife opened a business last year and that's taken a large portion of her time.At the beginning, everything was great, she was in advanced placement in 5th grade and did all her homework, as did her younger sister. The next year, the eldest was, again, placed in advanced classes. But that's when I began having issues with the eldest not turning in her assignments. She did them, just didn't turn them in. Her test scores were great, but the weight of 0s on her homework and class work dropped her would-be As to Cs and Ds.This is continuing into this year, her 8th grade year. Her biological father is only present when it's convenient for him, but when in touch, he's sympathetic to her school plight and excuses the poor grades, as they're "still passing".This is my third year trying to overcome this because I know she's so much more capable. Her sister started 6th grade this year and has no issue, to date, to the adjustment.As parents, our school system has an online tool to check the progress of their grades, missing assignments and absences. Unfortunately, the teachers end up recording graded in bulk rather than as they're turned in. I don't fault them in this case, but it makes it difficult to maintain.To date, I've tried grounding if xx wasn't done by yy date. That was a short remedy. When that stopped working, I tried communicating with the teachers -- this resulted in her having to write her weekly assignments for each class in her agenda book and getting a teacher signature, that I then checked daily. This seemed to have fixed the issue, or so I thought.This year, I wiped the slate clean with her, and communicated that this year she needs to show responsibility and that means getting assignments done on time, all in hopes of me not being overbearing and prepping her for high school,where there's less hand holding.I've maintained my consistency all these years, asking daily, how school was, what kind of homework and if they need help. If homework is assigned, we get it done as soon as we get home from the Boys and Girls Club.I'm at whit's end with this and not sure how to fix it. Any suggestions. via /r/Parenting http://ift.tt/2eijBg4