You are not being unreasonable at all. Probably what is happening is that the dad obviously has no idea how much time and organization it takes to get a large group of toddlers and preschoolers ready and out the door to do a school run. I take my son to the bus stop one block away every morning. It takes us 30 minutes (25 minutes of getting dressed and loaded into the stroller etc, and 5 minutes to walk). I am impressed that you can do it in 10 minutes! I would do exactly as you said...tell him that from now on he has to arrive by 8:15 or drop his son off himself. It is fair and reasonable.