Transcript for Jackie Evancho Preps for Inauguration, Transgender Sister Preps for Gender Confirmation Surgery
We're in Washington, D.C. Where in just hours the 45th president of the United States, Donald J. Trump will be sworn into office. And a talented young singer will kick off the event. Jackie Evanko has been getting flack for agreeing to sing the national anthem. What should have been pure joy has become a battle of career, her country and her family. Here's juju Chang. ??? There will be never be ??? Reporter: Just listen to a few notes. ??? ??? Reporter: And you'll realize why Jackie Evanko has been called the girl with the voice of an angel. ??? ??? Reporter: But in a matter of hours, she'll step onto the biggest stage of her career, singing the national anthem at Donald Trump's inauguration. She's 10 years old, with a timeless voice. Reporter: Jackie was discovered on "America's got talent." At just 16, the classical singer has traveled the world, singing for heads of state. The pope, an emperor, even the Obamas, twice. I've done it before, and now it's become a new goal of mine to perform for as many presidents as possible. Reporter: But when she offered to sing at the inauguration, it triggered an onslaught of criticism. So you do all your recording in here, right? Yeah. Jimmy: We met her in her Pittsburgh music studio, where she told us she's not naive about some of the hate she's getting online. What's the most painful stuff that you see on social media with you? Reading about my own hate really doesn't bother me. It's reading about my family's hate that really gets to me. ??? ??? Reporter: Those critics calling her decision to perform career suicide. Especially after so many artists have said no. Actress and singer Jennifer holiday recently backed out after backlash from furious fans, telling "The view" -- The gay community through "The daily beast" was able to say it's not just we want to be married, there are other things going on you're not aware of. I'm like, okay, thank you, I'll pull out. There are a lot of artists who won't for political reasons. I pay no attention to it, because I'm a 16-year-old and I don't involve myself in politics. It's not a political thing for me. Reporter: They assume she's a trump supporter. Something she won't discuss. But part of the criticism stems from the trump team's gay rights record. Which may put Jackie at odds with her own transgender sister. Born Jacob. Juliette Evanko is also an aspiring artist. Right now, I'm already receiving backlash from both sides of what my sister has decided to do. Jimmy: I . Reporter: It's tough? Jackie is singing for the inauguration, and I'm really proud of her with it. Reporter: Her sister gave us a tour of Jackie's career highlights in their Pittsburgh home. Juliette hopes to one day model. It's Italian "Vogue." That's extraordinary. Reporter: This fall, she made the homecoming court at pine Richland, the same high school as her sister, who say sophomore. You guys are competitive about everything you do, right? Oh, yes. Everything has been a competition since we were little. I actually wanted to be a singer before Jackie did. Reporter: Is that right? Yeah. So that little bit of competition has created all of this. Reporter: Sibling rivalry for sure, but Juliette says they've always been devoted sisters, even when she was known as Jacob. When I would play make-believe games with my sister, I was always a girl. Reporter: You and Jackie played barbies together? Yeah. Although there was a problem one time when Jackie cut off my aerial Barbie doll's hair. Reporter: Hair cuts figure prominently in your trauma as a child? Yes. Reporter: It happened backstage just before a ten 13-year-old Jacob was about to step out to sing a duet, "I see the light," with his sister Jackie. I was growing out my hair at the time -- Reporter: To make you feel more feminine? Yes. Reporter: But the producer of the movie had a problem. ??? ??? They're like, your hair looks all shaggy. And they're like, we're going to cut it off. Reporter: Because on the outside, you looked very much the proper boy? Yeah. On the inside, it was kinda killing me, because I wasn't a boy. Reporter: It would be years for Juliette summoned the courage to come out publicly as Tran at age 17, thanks to the support of her family. Juliette was always Juliette. It was me saying, oh, it's a phase. And now, I realize that that was not the case. ??? ??? Reporter: Jackie even made a music video in tribute to their life-long sisterhood, to the Ed sheeran song "All the stars." We kind of want it to represent us and for kind of everyone out there who is going through the same thing, and in honor of my sister. They're acting like we're these monsters. Reporter: And her bravely as a transgender advocate, joining forces with lambda legal, filing a lawsuit in Pittsburgh, after they voted to ban transgender students from using the bathrooms that they identify with. It invited even more discrimination, and I was called some pretty awful things. Reporter: To your face or online or both? Um, people would admissibmumble it as they passed me. I remember last year, trash was thrown at me. Reporter: It's the type of anti-lgbtq law that Mike pence, the next vice president of the United States supported when he was governor of Indiana. Why is this a big deal? Being able to walk into a women's rest room without thinking about it is kind of empowering in a sense. Because we get to be us in the most mundane ways. Reporter: You are just as involved in Juliette's life as you are in Jackie's? Absolutely. I mean, they're our kids. And whatever happens, if we feel it's wrong, we do what we can to help. Reporter: But during one of the most momentous weeks for both of their two daughters, this tight-knit family will not be together? Normally we'd go out and support Jackie, but this is a big moment for Juliette, and I don't know if you want me to talk about that or not. It's gonna be out there eventually. We're just going to have her srs procedures done, sex reassignment surgery. Reporter: A major milestone. So while mom's accompanying Juliette for the biggest transformation of her life, dad and their two younger kids will be in D.C., cheering for Jackie. Ever since she first came out, I've always been really excited for this day for her. So I guess we both just wish we could be there for each other. It's unfortunate that it's at the same time, but we're there in spirit. Reporter: You're getting teary-eyed? Yeah. Reporter: Why? Because I love her. She's my sister. And I'm happy. Jimm Reporter: You're happy for her? Yeah. Reporter: Their sisterly bond, unbreakable. She's a beautiful singer, she's a beautiful human being, and that's the way I look at it. Reporter: For "Nightline," I'm juju Chang in Pittsburgh, Pennsylvania.
This transcript has been automatically generated and may not be 100% accurate.