Overnight rates

I know this has been asked so many times but wanted some input.
This may start in January so I have some time to figure it out. Big daycare boy will be 2.5 yrs. Teeny daycare girl will be 6 months. Mom is in her 4th yr of nursing so has to do her preceptorship which means 12hr shifts and overnights. Dad works 4-12 and honestly sounds like he's not much help with the kids. I told her we'd talk and see if we could work something out regarding her new hours.
My standard hours are 7:30-5:30.
Rate for 24 months and over is $35 full day, up to 9hrs, includes lunch and 2 snacks. Rate for under 24 months is $40 full day, up to 9 hrs. Doesn't include formula or purees. In my contract I have an after hours care rate of $7 per hour.
I'm unsure of how to charge it out. The difficult thing is I really like this family but by May at the latest they will be gone as mom is done school. The possibility to get them back is there if mom gets a job but that won't be until at least July because of licensing.
So I was thinking $58 for baby girl and $52 for big boy for the extended day. That includes the extra meal (supper). I was thinking of charging her the same above rate for the over nights plus a $30 premium per family. Does that seem fair to the family? Does that seem fair to me? We don't do much as a family during the week and I rarely go out unless for groceries and that can be rescheduled.

Your normal day fee of $35 and $40 is similar to rate here. We tend have flat rate for all ages but $35-$40 seem most common based on experience and if meal provided.

I think fee is maybe little low for overnight.

Most charge $100 for overnight if no overlap to normal hours which mean provider able to have overnight child as extra income. Most charge $100+normal daily fee if child going be in daycare during normal hours operating. So if child being dropped off at 3pm that mean space must be allocated to child and parent pay for that space. Then overnight fee. If child gone before daycare open in morning, then that's it. If child still there when daycare open in morning, might be another charge because again, taking a place.

I understand you not go out much as family during week but the $100 overnight is because you will not have option to if want to. It mean evening time is tied to house. It mean no option for grocery shop, bank run, routine task when business day end. It mean no going out supper on special occasion or evening activity for own children. You have be fairly compensated for losing personal time.

I charge 10$ an hr for over night care. So from my closing time 5pm to my opening time 7am its 10$/hr. 140$ for 14hrs.