Demi Lovato Poses with Pregnant Sister Madison De La Garza in Rare Family Photo: 'Baby Sis Is Having a Baby!'

Demi Lovato can't wait to be an aunt!

On Sunday Sept. 22, the "Heart Attack" singer, 32, posted a rare family photo to her Instagram, as she celebrated her "baby sis" Madison De La Garza's pregnancy with her first baby. The Desperate Housewives alum, 22, smiled in the center, while Demi, her older sister Dallas Lovato, 36, and their mom Dianna De La Garza, 62, all excitedly cradle Madison's baby bump.

"My baby sis is having a baby!!" the musician wrote in her caption. "I love you @maddelagarza and I can’t wait to meet your little angel 🥹🖤"

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Madison initially announced her exciting baby news on Thursday, Sept. 5 with an Instagram post showing her baby bump while posing with 27-year-old boyfriend Ryan Mitchell. "Oh Ryan, how I love you," she captioned the photo.

"Thank you for making all of my dreams come true. ♥️ Baby Mitchell 10.24," she added, announcing the baby's due date is set for October.

In the comment section, Demi wrote, "I love you and this baby so much already!!" She later reshared De La Garza's announcement on her Instagram Stories, writing, "Congratulations baby girl. I love you so much!!!"

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Madison was showered with love from more family, friends and costars in the comments. "Woohoooo," Dianna said in her own remark. "I’m gonna be a REAL GRANDMA D NOW!!!! Love youuuuu!! ❤️❤️❤️."

Madison's cousin, Cruel Summer star Braeden De La Garza, also shared his support. "My uncle training will finally pay off," he wrote as Dianna commented with laughing emojis.

It appears Madison only went public with her romance with Mitchell this summer. "My whole world ♥️," she wrote in the caption to a photo added to her Instagram grid on June 13.