this is tough, i'm a trained child counselor. btw i hate the label of conduct disorder. i think it's a childhood bullshi!t diagnosis. i prefer "Narcissistic Personality Disorder traits". NPD is incredibly common in the world. & it's the most commonly passed on personality disorder by parents & peers, w/such a wide spectrum of traits. kids can show traits & not ever have the full disorder. & kids can show traits & grow into the disorder.
a lot of therapists i have talked to have theorized that bullying & NPD traits are showing up in kids so much b/c parents aren't raising them as much as they used to. more kids are being raised by peers online than ever before. social media, mass media to binge watch. too many kids don't have enough time w/adults period. & the lack of lessons at home about socializing has ended up w/a lot of kids showing NPD or "Conduct Disorder" traits. i prefer teaching kids about NPD b/c it's better for their safety as they grow and make friends in all grades & college.
my best advice is to teach your kids about NPD for their safety. be honest. & introduce other, safer friends. if you have to, take them to a church that you approve of to make friends. but i've found that parents have to be the ones to introduce the "type" of friends they would like them to have for safety. you can't just teach them. church or volunteering with your kids can both bring you and your kids into contact w/safer kids.
i'm not religious at all, but religions offer you a safer environment, with many choices of churches to find your kids the right safer friends. i've found that you can't really control who your kids befriend, as i'm sure you know. or evict people from their lives. all you can do is thin the bullying herd with bringing safer people into their lives & being honest w/teaching your kids about what the consequences will be for those who bully (or associate with bullies) in life - domestic violence, alcohol abuse, divorces, debt, unwanted pregnancies, being hacked, being stalked, drug use, crime, chaos, lost jobs, etc. i've found once kids start experiencing bullying, they're ready to start learning the consequences that will follow bullies.
i'm so sorry, but it really does seem like kids have to grow up so much sooner these days. not trying to tell you what to teach your kids. i've just been down this road w/too many kids whose parents tried to keep them kids while they were being exposed to bullying & drug sales.
my best advice is just total honesty using wording they can understand, making yourself open to their questions, and church or volunteering for safer friends. best of luck to you. you're all in my thoughts, really.

Thank you for your advice. My son actually does volunteer with young children already and my daughter is also starting to and I have always shown them that I volunteer and that volunteering is a fun positive thing to do and I am already seeing that it has influenced them to volunteer which is great! We also are not religious, but for my kids whole lives, we have been close friends with a family who are regular churchgoers and have spent every Christmas Eve and Easter and sometimes other times with them at their church. It’s true, my kids have met much nicer kids in church or volunteering situations. Most of their friends that they are around on a more regular basis though are kids they meet at school and it is just so disturbing to see how the majority of them show signs of abusive psycopaths, (which I know about because I was married to one and went through a domestic violence program to learn to get away from). Yes they may also be narcissistic, but also every definition of psychopaths, sociopaths, anti social personality disorder and abusers clearly describes all of these kids perfectly. I just find that very disturbing and strange that this is the majority of kids. You are right about most parents not spending enough time teaching their kids how to behave! But I still think it’s strange that so many kids don’t have any natural feeling of empathy, compassion or conscience. I do also find it strange that so many parents have children and then don’t teach them how to be decent human beings! There has to be something wrong here! I am always honest with my kids about all of this and have been doing my best to teach them and at the same time give them the amount of freedom appropriate for their ages and maturity levels. When I talk to my kids about the way their friends are treating them, they usually respond by saying that they know it’s not very nice, but without being friends with those kids, they wouldn’t have many friends, and since then are both very social, even if they do find a few nice friends, they are going to want to hang out with kids their age all the time, which means having as many friends as they can, including the mean ones, which sadly is the majority of them. Thanks again for your advice, I will continue to teach them to be aware of this and to try to find more activities for them where they will meet nicer kids

I have to agree. Have your kids get involved with mutual interest groups. generally those in groups that are out to improve the world attract nicer folks who care about others and this world.