The World's Okayest Pastor

So question to all of you parents out there: When is it okay for a non-parent person, me, step in and do some parenting? Let me give you an example: This past Friday night my mother and I were stopping at a store/restaurant to grab some dinner. We were at the end of the line and there was a couple that had three boys I'd say age 7 and younger that were running around getting into everything. The oldest two boys decided to run and jump at a lady, causing her to fall. This woman clearly had a medical diagnosis that limited her mobility. The boys did not say anything to the woman and went to playing in the cold display case. After helping the lady up and making sure she was okay my mother and I  looked to see if the parents were handling the situation. They were not, they were choosing to ignore their children's actions, who by this point were playing with glass drink bottles. Needless to say my mother and I had had enough and asked the two oldest boys to leave the drin...