I took DS to the bike track that has "road rules" at one of the local parks the other day and there is a girl who would be in her 20's in an electric wheelchair that is quite often there and she drives herself around the track but on this occasion she seemed to be causing confusion and stack ups by going the wrong way around. DS being only 2 does goes the wrong way sometimes on his scooter and he crossed her path making her stop. I apologised to her explaining that he is still learning the rules and she said that was ok, she understood and I moved DS to another part of the track. Then this parent went over to her and says to her in a quite aggressive manner and loud enough for everyone at the track to hear that if she looks at the sign she could see that it says "one way" and she was going the wrong way and if she went the right way the kids would stop having accidents. While this is true her manner was quite aggressive. I think this parent had already had a go at her before I got there as well. The girl got all confused trying to turn around and then rode off in tears. I felt so bad for her. I didn't quite know what to do. I didn't want to start an argument with the parent while DS was there and the girl had already gone off and did not come back. What would you do?