I held a flight for 10 minutes to allow 20 out of 40 school kids to make it and join their group. Fortunately noone wondered why I had a snow delay in August. Luckily we don't use ACARS. Common sense must prevail. Plus, I think the school teacher crying in the forward galley would have passed out if i'd left half her kids in the wrong country. At least that was 1 happy customer.