Nick and Joe Jonas showed off the latest addition to their family with adorable Instagram photos.

In Nick's photo, the 21-year-old smiled as he held his niece in his arms for the first time and the newborn stared straight into his eyes.

"My beautiful niece Alena Rose," he wrote as the caption.

The other addition to the Jonas Brothers also documented the moment he held the newborn in his arms.

"Welcome to this world Alena Jonas. #littlebaby #shessosmall #woah," Joe wrote as the caption on Feb. 5.

Their older brother Kevin, 26, welcomed the baby girl with his wife Danielle, 26, on Sunday. Nick also revealed Kevin's excitement with being a first-time parent.

"He is in love with this baby, it's ridiculous. He sends me pictures every 10 minutes," Nick told E! News. "I think it's just like the joy of his life right now, so I'm excited to go [see] him."

The proud father also took to his own Instagram page to post several photos of the newborn. In one picture, he kissed the baby on her head as she slept on his shoulder and captioned the moment, "It's still blows me away this is my life!"

His wife of five years also expressed similar thoughts on her Instagram. The new mommy uploaded a picture of the baby sleeping in a pink onesie with the caption, "So excited to have her home. I can't believe Kevin and I have a family #soinlove."