Problem is overlap in that day shift is often 7-3 and second 3-11 but you would have both kids at 3 when one set of parents is coming and other has to drop off to get to work.

Other option to look into especially if you have a hospital nearby is doing the 12 hour shifts. For that parents generally work 7am - 7 pm s need care about 14 hours ie 6 am to 8 pm. That still gives you a full night's sleep. Fee would be about 1 1/2 times your daily rate because of the 3 meals and 3 snacks. But also they would only be there 3-4 days a week because they do so many days on and so many days off on a rotating schedule which is set well in advance.