Many years ago I had an issue with numbers and a complaint to the ministry. When they spoke to me they said it went by contracted hours and if one parent was supposed to come at 3pm but didn't show up till 3:20 that wasn't my problem so I was free to go by the contracted hours of one done at 3 and one starting at 3. Back then of course they weren't so hard by the books and common sense reigned more with the idea of the potential overlap wasn't considered a big deal. Now of course insurance would use that as a loophole for sure.