I charge a higher rate to teachers from Sept to June but then they are allowed to bring their child one day a week in the summer at no cost. If they don't well I have been paid anyways. I also ask for a deposit every June towards the first two weeks of care in Sept and if they change their minds over the summer and don't come back they lose it.

In your case there are other circumstances too being they are neighbours and what you have been charging them up until now. I would probably do full time pay from Jan to June and then either a 2 day or 3 day charge in the summer. What you don't want to run into is no fee and then child comes over to "play" with your child constantly all summer meaning you have expenses anyways.

I also find for the 8 weeks teachers are off that what some like is to leave the child for the first week of July and take the time to get house organized that they didn't do all year and then they are back to work anyways for some the last week of August so that only leaves 6 weeks in the middle and toss in vacation weeks and there really isn't that much to the summer anyways although it seems like a lot longer some years.