Hi there - welcome to the group ! =) I think I would just tell this Mum the truth about how important it is that he arrive on time so that you and the kids can get on with doing fun stuff. It's kind of you to be tuned in to her mood, and obviously, use as much tact and diplomacy as you would in any other job when you have to have an unpleasant conversation with someone. No need to make her feel worse, right ? =) Try suggesting that she build an extra half hour/forty five minutes into her morning schedule - if she arrives a half hour earlier than you expected it's not a problem for you, is it ? I would absolutely avoid offering to do pick up - like you said, if he's running late, you don't have time to wait on him. Good luck !