Amber,
I have been involved in the Sunday School at my church since 2006. At that point, there were 2 students, a brother and sister, whose mom worked at the church, and they were brought up there etc. They quit coming in 2007. Since then, membership swelled to 12-18 kids (at different times) NONE of whom had ANY parental involvement in the church, and ALL of whom have some sort of family troubles.
At first, I thought it was difficult too. But these kids have taught me SO much over the last few years! One of my students, a ten year old girl, shows such faith in God, such grown-up style prayers, it blows me away. She recently wrote in her prayer journal that she wants to be a Sunday School teacher when she grows up.
It's hard, somtimes, because you don't know who is going to show up or who will be grounded from church this week. (Yeah, they get grounded from church!)
I went to a Sunday School Teacher's Conference last year and mine was the only Sunday School represented there that had NO parental involvement whatsoever.
Curriculum designers need to rethink the way they make curriculum, because the definition of "family" is changing, whether we like it or not. You can't gear everything toward "mom" because they may not have one!
For Father's day last year, we did a lesson on God being everyone's father (because NONE of my kids have a father present in their lives) and even though one kid was a little sad in the beginning, they all felt better when they left.
I think what's REALLY important to these kids is having a church family to support them, because many of them don't have anyone in their life that relly gives a crap about them.
Just show your kids love- that's what God is. He'll handle the rest.