'Teen Mom' Leah Messer Has a Heart-to-Heart With Daughter Aleeah About Sister Ali's Muscular Dystrophy in Exclusive Sneak Peek

Teen Mom 's Leah Messer wants to make sure all of her daughters are getting the help they need. Leah sits down with 14-year-old daughter Aleeah in a PopCulture.com exclusive sneak peek of Thursday's all-new episode of Teen Mom: The Next Chapter , looking to have a heart-to-heart with the teen about how twin sister Aliannah has been managing her muscular dystrophy.

When Leah brings up the idea of Ali being "a little bit more independent" and using her wheelchair more often, Aleeah assures her mom, "I'm always going to help her walk and do physical things she struggles with." Asked if she thinks her sister "fully accepts" the diagnosis she first received in 2014 , Aleeah admits, "No."

"I don't think that she realizes that it's there and she thinks that she can do everything that we do," the teen continues, "but when it comes to it, she realizes that she can't. So then I think it tears her down." It's hurtful to see, Aleeah shares, agreeing with her mom that Ali using her wheelchair more often "would be more beneficial."

"Why do you think she refuses to use it sometimes?" Leah asks her daughter, who theorizes Ali wants to stay away from being "different" than her peers. Leah insists that even though it might be difficult, it's important for their family to work together to support Ali's health both now and in the future.

"I think we have to find a balance in enabling her or helping her too much because then it's preventing her from the future she deserves," she explains. "I think we're at a place where we help her realize that it's OK to be different [and] to accept that reality."

The MTV star asks, "What is she going to do when you guys go to college? Or what if you guys aren't in the same classes next year? She's not going to be able to rely on you. She's not going to be able to rely on me. And you both have your own dreams and ambitions."

Aleeah acknowledges that she does eventually want to leave West Virginia behind and become a marine biologist. "My hope is that you fulfill everything that you set out for yourself," Leah tells her. "So I'm going to need you to kind of break that chain [with Ali] a little bit and pursue you too, OK? And not feel that pressure."

Teen Mom: The Next Chapter airs Thursdays at 8 p.m. ET on MTV.