Visit on 11/5 was cancelled but family paid. They never cancelled on Rover. Now they want to reschedule and don't need to pay again.
I suggest you contact Rover Support directly because you can't just substitute another date. The insurance and backup support would not apply to the new date.
Did the owner want you to keep the booking fee for the date they cancelled? If not, it should have been cancelled by the owner or you letting rover know "the owner" cancelled. Of course by now you would have been paid for it. But, it also depends on your cancellation policy. You can contact rover and have rover keep enough of your up coming payments to cover their next visit. It's best to stay on top of cancellations. Sometimes if my customers cancel or pick up a day or two earlier than planned, I remind them I am on "Strict Policy" and they tell me to keep the money. Just a learning experience and curve.