This happens almost every time we have baptism. Parents who have come to Christ are baptized with their children. We see this happen because of a change we made a few years ago.
Here it is. We have parents attend their kid's faith commitment / baptism class with them. It is required. No drop offs.
Then we are very intentional in the class about not only sharing the Gospel with the kids, but with the parents as well. This can be as simple as saying, "Parents, you've heard what it means to enter a relationship with Jesus. If you haven't taken that step, we would like to invite you to do so as well."
And that's when the power of the Gospel reaches parents. There is a family I am baptizing this coming weekend. After a recent baptism class, (we have two classes - first week is salvation and second week is about baptism) I sat down with this single mom and her daughter who had attended. They both wanted to be baptized. They shared how they had went home and prayed to receive Christ's forgiveness together after hearing the Gospel in the first class. Mom and daughter...both reached for Christ.
This story could be told hundreds of times over. Be intentional about sharing the Gospel with not only kids, but with their parents as well. Remember...
"When you reach a child, you change a life. When you reach parents, you change an entire family."