Looking For Backup Nanny Help

My husband and I are looking to establish a relationship a nanny who has a flexible schedule and able to help with last minute care needs due to daycare closures or sick kiddos. We occasionally could use help with daycare pickup and staying with the girls until one of us gets home from work. My husband and I are medical and work longer shifts, which makes daycare pickups challenging some days. We can look at options for more hours if desired. We would also love to find someone who would be willing to watch our girls overnight/long weekend. I realize we are looking for a unicorn.