Group Leader Registration Options - allow group leaders to edit the number of volunteers per shift for number-based groups

We have some volunteers who volunteer individually, with family members, and as leaders of groups of 15+. These volunteers have been assigned as group leaders of Number-Based Groups, but their having to contact us for every single shift to adjust the number of volunteers is time-consuming for them and for us. It would be helpful if group leaders had more ability on their end to edit the size of their group for each shift. This would also be helpful for parents who volunteer with their kids regularly, because the number of family members volunteering can vary.