Best money we ever spent was on a 6 foot fence that enclosed our 1 acre lot.My only regret is not having enough money to fence the front yard!
And I love my stinging nettle.Potted and portable to keep the front yarders away. You have my sympathies! Our last home was a condo,and the kids played right in front of our home.Would not have been so so bad had they not shunned my kids.So we heard them all day,and my little ones could not understand why they ignored them.Now we have elderly neighbors and love the peace.I can hear kids in the neighborhood next to our busy main road,but I don't miss having families right next door.
Be careful what you do,because some neighbors react by becoming more aggressive/destructive when you put your foot down. You need to nip it though otherwise you pay for a home you can not enjoy.For now I would just keep sending them home citing the damage previously done. " You damaged many things the other day,and I can not have you coming over right now." Hopefully they will leach on to another family when you become less avaliable.