One thing that works, my son's elementary school use to have parents do this. We had to look at the homework and sign it as well as tests that all kids had to bring home for parents to see, sign and ask any questions to the teachers, rather through phone or written letter.
I also was a teacher's aide there for 5yrs before going to college, then I had to quit. Asking to see your daughter's homework before she relaxes for the evening really will help and make her aware that she just can't tell you she did it.
The signing by parent was at our school and not optional, but you do not have to do that just look at it. If she has to have a homework log to copy down assigments given for homework you can check the homework to what was assigned that day. This will make it hard for her to try to get out of doing it. One of my son's teacher, that he had for 2nd grade noticed he took longer than many to complete work, so at home she told me and some moms to put a kitchen timer on when they begin homework starting maybe with 30 minutes to 45, helps remind the child that many things have a time limit. It worked, he didn't like it but it worked. I hated to do this but he use to start gabbing with me and sort of put off getting the work done, so it also helped me to remind myself to not gab with him till his work was done.
Some teachers were brushing it off telling so many of us that our kids were ADD and have them tested, the psychologist said he wasn't, just being a kid. He also said he and his colleages (sp?) have been seeing over the years many parents and teachers jumping on the "ADD" wagon, it exists but not as high of a percentage as teachers and parents claim to see. Some of it just requires parental attention, structure and teaching self discipline.
Yes, all this takes time, patience, and rewards sometimes, but it works. Also when there is family problems kids will also distract, they feel the upset and not always know how to express it, nor do they always understand why things between parents aren't going well. What use to be sad is when kids took it upon themselves to feel guilty, that they were the cause to mom and dad's problems.
I hope I haven't talked off your eyes here, but just wanted to share some things. I think it is a good idea too, that when there are family problems, such as divorce, seperation, etc. that kids can benefit from family therapy, or see a child psychologist, a person unbias, outside of the family.
I wish you lots of luck with all of this, I could imagine what a toll it is having on you. Hang in there, and always feel free to come here and talk/vent.

Take care now,
DE