* As the Oscar-winning film "The Sound of Music" celebrates its 50th anniversary, we couldn't help but wonder what was really going on behind the von Trapp curtain (before Maria made it into lederhosen). Did Brigitta secretly resent how much attention Gretl got? Was Friedrich jealous of Kurt's killer falsetto? Did they line up in descending height when no one was watching? In other words what are the struggles and rewards of being in showbiz with your siblings? Since the real von Trapps are no longer available for interviews, Playbill.com decided to ask 12 brothers and sisters currently performing on Broadway and beyond about their relationships with their equally talented siblings on and offstage. Apparently, there's a lot more to it than putting on puppet shows at your parents' house.

Jessie and Abby Mueller

This April, fresh off her Tony-winning run as Carole King in Beautiful: The Carole King Musical, Jessie Mueller will be honored with the Sarah Siddons Society's Actress of the Year Award in her hometown of Chicago. It's an award that has recognized talents such as Helen Hayes, Patti Lupone, Julie Andrews and Liza Minnelli, but to make Jessie's night even more memorable, she will be joined on stage by her whole family for a special von Trapp-style performance. Mueller's actor parents Roger Mueller and Jill Shellabarger will introduce their four children, all of whom followed in their footsteps.

Jessie's sister Abby is in the current cast of Kinky Boots on Broadway and their brothers Andrew and Matthew are successful Chicago actors. Abby credits their parents for preparing she and Jessie for the Broadway stage. "[We learned] the value of a strong work ethic and the privilege of being part of an ensemble," says Abby. "If you're a kind, authentic person, hopefully people will respond in kind." Their Midwestern values paid off last spring when Jessie won the Mueller' family's first Tony Award. "My parents were sitting with my sister right behind Neil Patrick Harris during the awards, so Rog got a lot of screen time," says Abby. "Seeing my dad's face every time they panned to Neil was pretty priceless. He and my mom were absolutely floating that evening. They looked like happy, beautiful movie stars and I think Jess and I would agree that was one of the best and most rewarding things."

But as far as her place in the family, Jessie says nothing has really changed and she wouldn't have it any other way. "The view from outside may look a little different now, post-Tonys or other measured benchmarks of 'success,'" says Jessie, "but my family knows me. They're the ones I can trust, and the first ones who would let me know if I got out of line and started acting like I was hot poop!" Abby says although they have similar features she's never felt in direct competition with her award-winning younger sister. In fact, the only time they went in for the same role was when they auditioned to play their actual father's daughter in a production of State Fair at Marriott's Lincolnshire Theatre in Chicago. Neither of them got it. "I guess they just didn't buy it," says Jessie.

Sydney and Jake Lucas

There will be no such thing as spring break in the Lucas household this year. But even with a long winter that's yet to thaw out, the 11-year-old Sydney and her 12-year-old brother Jake could care less about a Florida vacation. They are already having the time of their lives in the rehearsal room. This month Sydney will be making her Broadway debut in Fun Home, reprising her Obie-winning role as Small Alison alongside Michael Cerveris and Judy Kuhn, while Jake will reunite with his Peter Pan Live! costar Kelli O'Hara for the Lincoln Center revival of The King and I.

According to them the only thing better than being on Broadway at the same time would be starring in the same show. "I love performing with him because we're very compatible," says Sydney. They recently sang the National Anthem together at a Knicks home game and Sydney says her big brother helped calm her nerves. "I told her to breathe in through her nose and out through her mouth," says Jake, "and that all her friends were watching and they were going to love it. I have this really low soothing voice." Only 13 months apart they feel more like twins than regular brother and sister. "We're best friends," says Sydney. But that doesn't mean they aren't competitive with each other. "We'll say things like, 'I can drink this much water in 10 seconds. Can you?'" says Jake. "Or I can go faster down this hill than you on my skateboard," adds Sydney. They're happy to be different genders so as not to compete with each other for the same role, but if any casting directors are reading this, they would love to star in a musical together soon. "We've already done a movie and a commercial together," says Sydney. "It's definitely a plus having each other around."

Lindsay and Michael Mendez

"Someone needs to write a siblings musical we can all be in," says Lindsay Mendez, speaking for all the Broadway brothers and sisters out there. The Wicked and Dogfight star is dying to work with her younger brother, Michael (Chaplin) but few musicals exist that include juicy roles for a boy and a girl who aren't romantically involved. In fact, Michael lost a role in the 2007 revival of Grease because he would have been playing the Roger to Lindsay's Jan. "The guy who played opposite me left the show and that would have been a great role for Michael," says Lindsay. But after Michael auditioned, both the creative team and the Mendez's decided it would just be too weird.

Michael was recently given another opportunity to join the Burger Palace Boys at the Northshore Theatre in Massachusetts and from there he went on to the North Carolina Theatre for a production of Billy Elliot that wrapped in February. When he's not traveling, he and his big sis live about 20 blocks from each other in New York. They share a lot of the same theatre industry friends like Lindsay's Dogfight costar Josh Segarra, as well as a car. (Who pays the EZ Pass bill is up for debate.) "We have things that keep us involved in each other's lives," says Lindsay. Still, it might be a good thing no one has written that brother/sister musical for them just yet. "We would probably get in a lot of trouble because we make each other laugh so bad," says Lindsay. Michael agrees. "I can't imagine doing a scene with you at this point," he says. "It would take a lot of rehearsal."

Megan and Robert Fairchild

Growing up in Utah, Robert Fairchild channeled Mike from A Chorus Line. Everything his older sister Megan did, he wanted to do, too. "We've had parallel lives because I always did everything she did," says Robert who is making his Broadway debut this spring in An American in Paris. "She started dancing, I started dancing. She started playing the violin and I started playing the violin. It was like the 'I Can Do That' kind of thing." He ended up following Megan to New York where they both joined the company of the New York City Ballet. One night Megan's partner was injured before the premiere of a new ballet, so Robert stepped in. "It went so smooth and there were no hiccups," says Robert. "We'd never really danced with each other before and we were like, 'Oh my God, it's like dancing with yourself.'" But the less experienced Robert almost collapsed out of exhaustion near the end of the performance. "I remember we were running backwards, holding on to each other and Megan goes, 'You're ok. You're ok.' To share my first big New York City Ballet experience with my sister was so special. She really led me through that whole process."

Now it's Megan's turn to follow Robbie—away from the ballet barre and onto Broadway. Although the revival of On the Town, in which Megan stars as Ivy opened this fall, Robert was cast as Jerry in An American in Paris first. When Megan went to see him in a workshop production of the new musical she couldn't believe her ears. "We're not singers, we're just dancers," says Megan, "but I was completely blown away. He pulled it off and I was totally in shock." When she was approached to audition for On the Town she said she "drew from his courage" and decided to try something new. Now brother and sister, who say they are closer than most siblings in the ballet world, are very excited they are sharing this Broadway experience together. So is their mom. "My mom is a bigger Broadway fan than a lover of ballet," says Megan. Their parents, who aren't performers (although Robert notes that his mother has "great feet for a dancer,"), will travel to New York for the opening night of An American in Paris, which they'll see three times as well as On the Town twice more. "After the opening of On the Town my mom said, 'I'm so glad we don't live in New York because I wouldn't have any money left,'" says Megan. "She would come [see us] every night if she could."

Abby and Milly Shapiro

For fun, 14-year-old Abigail and her 12-year-old sister Milly like to go to the club—and sing showtunes. In the past few years, since Milly outgrew her role as one of the original Matildas, the Shapiro's cherubic faces have become a regular sight at "Broadway's Supper Club" 54 Below, where they have performed their original cabaret show Live Out Loud, as well as a concert production of A Little Princess. Their favorite song to sing together is the Side Show ballad "I Will Never Leave You," which they often perform alongside "Together Wherever We Go" from Gypsy and "What is this Feeling?" from Wicked as part of what they call their "sister mashup." "It's really fun doing cabaret with my sister," says Abigail. "At 54 Below we get to interact on the stage and share inside jokes that we have at home." They love singing together so much that it's often how they make the best of household chores. "When we're doing the dishes or something like that one of us will start singing and the other one will start harmonizing," says Milly. Their mentors are the Callaway Sisters, who they recently saw perform at 54 Below. "The thing that I really like about them," says Milly, "is that they are very different from each other, but they both like to perform."

Sutton and Hunter Foster

Hunter Foster has been so busy this year he almost missed his little sister's wedding. He arrived in Santa Barbara, where Sutton Foster married TV and film writer Ted Griffin last October, just as the Tony winner was about to walk down the aisle. But, as they both know all too well: That's showbiz. That same weekend Hunter was directing his wife Jennifer Cody in The Rocky Horror Picture Show at Bucks County Playhouse and The Circus in Winter, a new musical he helped write, opened at the Norma Terris Theatre. "I have a sister and a wife in the business and I think that makes it easier, because everyone understands. [Sutton's wedding] was a perfect example of that," says Hunter. "He's like, you picked a really bad weekend," recalls Sutton. "I didn't know!"

Things won't be slowing down for either of them this spring. Hunter is directing the premiere of the new musical National Pastime at BCP in March and he and Ryan Scott Oliver's musical Jasper in Deadland is opening at Seattle's 5th Avenue Theatre in April, while Sutton stars in Darren Star's new original TV Land series "Younger"—about a 40-year-old divorcee who decides to re-enter the workforce as a 26-year-old—which premieres March 31. But despite their busy schedules the Georgia natives make sure they're available when it's important. "We go see each other's shows and we're there for each other no matter what, but sometimes it's hard to stay as close as we wish," says Sutton, who is currently splitting her time between New York and L.A. One thing Hunter made sure not to miss was the opening night of Violet last spring. He says Sutton's Tony-nominated role as the emotionally and physically scarred Southern believer really hit home. "I think it was hard in a lot of ways to do that show, knowing our history," says Hunter. "It's set in [the South] where our family is from and our mother had recently passed away. I sat with my dad on opening night, and I think that's probably the most proud of her I've ever been."

Now that Hunter is writing and directing, will there be a Foster collaboration in the near future? "That'd be great, if she has the time," says Hunter. And then he adds with a laugh, "I don't know if she'd take my direction." Sutton says she'd be up for letting her older brother boss her around again. "I actually think we'd do OK with that. I really trust him and he's so smart." She's often getting texts from friends who just auditioned for Hunter, letting her know what a great experience they had. "I think that's cool," she says. "Cut to me going in and auditioning for him, like, 'Hi, I'm Sutton.'"