When Lindsay Sebbo Willits began planning her wedding last year, there was no question that her little sister Julia would be a part of it.

"She was with me through all of that," Willits says. "We spent about a year together doing wedding planning."

When the July 7 wedding day rolled around, Julia joined her big sister's bridal party as a junior bridesmaid. "That's what you do when you have a little sister," Willits says.

When Willits talks about her 14-year-old little sister Julia, she isn't talking in the biological sense. Willits is Julia's big sister through the Big Brothers Big Sisters of the Black Hills program.

The two were paired seven years ago, when Willits was only 18 years old and Julia was 7. Willits remembers seeing the photos of Julia long before the two met. "The second that I saw Julia's picture, I picked her because we actually looked like we were sisters," she says.

Julia remembers their first official meeting. "I had pigtails and was wearing this funny sweater because my mom made me … and we went to the Royal Fork because that was my favorite," she says. "I thought she was really cool."

Willits had the same reaction.

"Right away, it was something different," Willits said. "Our conversations are never dull. Right away, she just made me laugh."

Since then, the two have become fast friends and adopted sisters.

They have sleepovers, see movies, go to dinner, ice skate and take hikes. "We do everything," Willits said. "She's the sister that I never had."

The two have more in common than just their relationship. Both have older big brothers but no biological sisters, and both have absentee fathers, says Julia's mother Denise. Those similarities have helped to cement their relationship. "Julia adores her big sister," Denise said.

Not only do Willits and Julia get together once a week, Willits' mother has developed a relationship with Julia as well. "Her mom? I love her," Julia said.

And Willits and Denise have also developed a friendship.

For Willits, her relationship with Julia has changed her life more than she expected. "You're not only mentoring a child; it makes you open your eyes to a different world," she said. "My life has changed dramatically … Maybe even more than hers."

Julia said she feels the same way. And nowadays, when people ask about her family, she doesn't hesitate with the answer.

"I tell them, 'I have an older brother and an older sister.'"