I agree with mickyc , two days a week is just enough not to be able to establish a routine with the child . It seems like the family is calling the shots , and do not care or understand the difficulty trying to fill the remaining days with another family . I charge a set rate for part timers , regardless of days .
I only work Monday to Wednesday and have most of my dcks all 3 days , I have one family 2 days a week I charge her the same as if it was 3 days . I know it's a high rate but I have no way of finding a family or want to have a family one day a week !