Advice please! - Horrid nephews

So I don't want to sound too *****y, but we had a family day organised on Wednesday this week as its school holidays.
Me, DP, DD, my sisters and their 2 kids each as well as their husbands.

Sister 1 has an 8 year old boy and a 2 year old boy, Sister 2 has a nearly 2 year old girl and a 6 month old girl.

Kids were off playing in the botanic gardens while we organised the picnic set up, had a chat, etc until we heard some squealing. It stopped then we heard giggling so we just carried on.
I later took DD and my 6 month old niece on a little walk to round up the kids for lunch.

So here's where the problem arises: my 8 and 2 year old nephews were being HORRIBLE to poor little niece, throwing rocks and sticks, singing nasty rhymes and then pretending to be sorry when she started to cry, making a few jokes, then starting the nastiness all over again!
I intervened quickly and they denied any wrong doing, niece also thinks she was just playing with the kids...

Later on I told Sister 2, she says Sister 1's kids do this every time and she is considering visiting them less frequently over time and eventually stopping contact if it does not stop.
Sister 1 doesn't seem to give a rat’s arse!

Typical excuses:
"Boys will be boys"
"She’s oversensitive"
"She’s jealous"

Any advice!?!?!? I want us all to get along and be sisters, but her kids are nasty and I don't want to put my second niece and DD through their crap as well :(

All I can give you is what I would do myself in this situation.

I don't listen to bollocks from kids that hurt others and pretend they are sorry. I don't argue with them but I will tell them that they won't be coming to play/on another picnic etc if they continue the behaviour.

If they kept it up I would tell them they aren't to play with niece anymore and send them off elsewhere until they can learn to play nicely.

And I do this with other peoples children, and I do it with my own...

hth

Thanks for the advice, but I guess it more the repurcussions from my eldest sister sister once the boys go running back to her telling stories of how their 2 year old cousin was the bad guy in the situation.

Boys will be boys just does not apply to nastiness and hurting another child.

It sounds like these kids have no chance of their parents don't see that it's a problem but they are the ones who will continually be told off or lose friends over it which sux for them but you see why other kids and their parents would do it.

The sister need a wake up call before the boys behaviour can get better.

I echo what Lulu says, when children are being mean (mine or others) they are removed from the situation and have to play on their own until they can learn to play nice. It rarely takes kids long to learn this lesson, usually one picnic spent sitting by the car or one playdate spent alone in their room when everyone else is on the trampoline.

The problem is, of course, your sister 1 who may not take kindly to her kids being excluded if she thinks they are doing no wrong. However there is not much to be done other than be honest with her and hopr that she sees you are doing this out of love and nothing less.

It seems that she will react negatively - you can't really change that. What you can do is put your boundaries in place and stay firm about them "I'm sorry but it's not ok to be throwing stones at my kid - why don't we get the football out instead?".

Is there anyway you can get her to see what her boys are doing, without the boys knowing she is watching?