Joel Madden Reveals When Daughter With Nicole Richie Changed Her Name

"We went home. We're like, 'You go by Kate at school?'" he continued. "She goes, 'Yeah, I like it.' And we were like, 'OK, great.'"

So, for more than a decade, their daughter has been going by her middle name.

"Everyone who knows her calls her Kate," he said. "If you've known her since she was 7, she's been Kate."

"It wasn't a big deal," he emphasized. "It was her middle name. It was just like, 'Oh, cool. That's cute. You're going by your middle name now. That's sweet.' Then, there was no discussion."

And now, her name has even become an unexpected litmus test.

"If you know her, you know she's Kate. People that don't know her would call her Harlow," the 47-year-old noted. "It's kind of smart, actually. She knows if someone called her Harlow, they don't really know her."

Joel knows how important it is to support his kids' identity. In fact, when it comes to fatherhood, Nicole knows that her husband of 15 years could write the anthem.

"I would say that Joel is a very shy introvert, who loves life, who enjoys life, who loves music, has such a deep passion for music, and anybody who shares that same passion, he will go above and beyond for," she reflected in a 2013 interview with Australia's 60 Minutes. "He is a loyal person, who has the most incredible family values of anybody that I've ever met."

Now, for a closer look at Nicole and Joel's simply adorable moments together, keep reading.