It has been nearly four years sinceJoan Riversdied — but her daughter,Melissa Rivers, says that her influence is still felt every day.

“I really notice my mom in my parenting,” says Melissa, 50, who is mom to 17-year-old son Cooper. “I’ll say something, and as soon as the words come out of my mouth, I’m like, ‘Wow. I sound just like my mom!'”

“And then I hear my father coming out, too!” she continues, referring to dad Edgar Rosenberg. “I was a big negotiator when I was a teenager, and my son tries that, too. Every time I say, ‘This is not my negotiation,’ I hear my father! He used to say that all the time!”

“One of my friends told me the other day that I shouldn’t negotiate with terrorists,” she says, laughing, “and I said, ‘Especially when you’re the hostage!'”

“I think I’m a fair mom,” Rivers says. “I’m very clear on what the rules are. I’m very clear that these are the parameters in which you may operate on. If you stay there, you’re good. If you don’t, your life will crash down around you. I always remind Cooper, ‘I can make your life miserable. Please don’t tempt me.'”

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Rivers tells PEOPLE that she sees Cooper as a way to keep her mother’s legacy alive.

“The best legacy that I can give my mother — that everyone can give their parent — is to raise a good and decent child,” she says. “One who gives back, and has a clear understanding of the understanding of not just being good, but doing good, as well. Cooper is my mom’s greatest legacy.”

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“My mother taught me this,” says Rivers. “When people ask me to do an event to help kids, the first questions are where and when. I can’t even begin to get my head around what it would be like to deal with cancer in your child, so if I can help other families who are going through this, I will.”

So wouldFashion PolicehostJoan Rivers have approved of the event? “Oh my God, yes.” says Rivers. “Obviously, my mother loved fashion, but she would have really loved to see it being used in this way, to make these kids feel good about themselves. This would have totally been her thing.”

source: people.com