Is there some kind of unsaid etiquette in how you should broach the behaviour of other children when it directly affects yours? (i've purposely avoided the word negative, discipline etc because i know everyone's perceptions vary so much).

I've been affected by this twice recently. First at a park which also has a path where small children ride bikes/ride ons etc. DS1 got off his bike but parked it next to the play equipment he went on. Me, dh and DS2 all nearby. I didn't even notice until i heard DS1 screeching and noticed another little boy similar age (3ish) had taken off with it, had already ridden it about 20 metres away. I went to console DS1, saying that he's probably just taken it for a ride but that its really rude to not ask for a turn first. I paused scanning the park for his mother.... assuming she would get him off and return it. About 5 mins past as my DS watched this kid enjoying his bike! If looks could kill! DS is not very verbal and very shy socially so would never approach anyone. But as nothing was happening i said, 'okay i think thats enough, lets go and ask him for it back'. We walked down about 20m where he was and i said 'we need the bike back now thank you love'.... he said 'ive been riding' (i was thinking um we realised that - don't you have any manners??? my DS would never touch anyone elses property without asking. Even my stuff! He will ask if he can borrow something from my room etc, taught him from a young age).

Then i realised only 2 metres away, the mother and family were on a blanket having a good old relax, fully in visual sight of her son... she just smiled and kind of mimed what i think was "sorry" but cant be sure because her smile looked more like a smirk. How could she just sit there and what her child take someone elses bike and not intervene? He ran off to some other play equipment and she just continued sitting there, not saying anything.... if she said something later i dont know, but it would have been pointless because a 3 year old can't really understand consequences if you don't address it while its happening.

I wanted to say to the boy, "you really should have asked before you took our bike" but wasn't sure if it was my place to do so.... is it??? We took the bike and i explained to DS1 that what the boy had done wasn't right and that you must always ask someone if you can have a turn or borrow something instead of just taking it, because the person can get upset. I think it was a good lesson for him though because now he knows how it feels.

We don't go to busy parks much so i'm not sure if this is a common thing and i'm over reacting? But i'd hate to think that if i was on my own what would have happened, because i couldn't have left ds2 by himself to walk all the way down to get the bike, luckily my dh was with him.

The other thing is going to a fun station, those indoor playgrounds. The one we go to has a sign on the gate "5 years and under only". Yet there's always older kids going in there. This really bothers me because we are trying to build DS1's confidence up by showing him that social crowded situations are okay and fun. Yet when he's on the bouncy castle and a huge clearly older child jumps on he freaks out and gets off. Today there was a dad with a toddler and 3 boys who were somewhere between 8 and 12. Its not a huge area, they were running around with the toddler, the dad was taking pictures... and well DS1 just didn't feel comfortable. I could tell as he kept stopping what he was doing and sort of standing back. Why do people ignore the rules? Do i have a right to say anything?? Also 2 of them weren't wearing socks, another rule. They often remind people over the loud speaker about the socks thing, but obviously they ignored it.

Just annoying and i'm wondering what the etiquette is?

I know if my boys were doing something wrong, i would definately step in, stop them doing it, explain why and offer an apology... and after explain to them that the right thing to do is apologise if you do something wrong to someone. (i don't believe in forcing children to apologise or shaming). But i'm definately pretty vigilant in making sure they're not doing anything that affects anyone else negatively.

What do you do when other parents aren't?