Maddie and Mackenzie Ziegler That’s why DoSomething.org , the largest organization for young people and social change has teamed up with Johnson & Johnson for a campaign called Birthday Mail.

Maddie Ziegler, left, and Mackenzie Ziegler, right, attend a special screening of "The Duff" at AMC Loews Lincoln Square on Wednesday, Feb. 18, 2015, in New York. Andy Kropa / Invision via AP ...

Mackenzie rose to fame as a child star on Lifetime's reality dance show Dance Moms back in 2011. ... Maddie Ziegler's younger sister Mackenzie, 20, ...

Maddie Ziegler opened up about the lasting effects of starring on "Dance Moms" as a child. She said her mother recently apologized for putting her (and her little sister) through the reality show.

Maddie Ziegler and Mackenzie Ziegler with their mother arrive for the LA Premiere Of "Ice Princess Lily" on November 16, 2019 in Santa Monica, California. Albert L. Ortega/Getty.

Abby Lee Miller said in a recent podcast interview that while she would potentially be open to speaking with Maddie Ziegler, ... everything for that child. ... I had a 360 deal with Mackenzie.