Ireland Baldwin wrote a letter to her baby sister on Tumblr. (Venturelli/WireImage/Getty Images)

Ireland Baldwin is apparently enjoying her role as older sister to new baby Carmen Gabriella. The baby was born to Ireland's father Alec Baldwin, 55, and his wife Hilaria, 29, on Friday.

"We are overjoyed to announce the birth of our daughter, Carmen Gabriela. She is absolutely perfect. @ABFalecbaldwin @IrelandBBaldwin," Hilaria Baldwin tweeted Friday.

After the announcement, the 17-year-old model posted a letter to her Tumblr blog titled "Happy Birthday," that welcomed her baby sister to the world and dispensed some sisterly advice.

"Dear Carmen, You have entered the world! Welcome! We have all been anticipating your arrival! By we, I mean a lot of people," writes Baldwin."There are countless lessons that I want to teach you, but I have faith that you will learn a majority of them on your own journey and they will help you grow. Though, I do want to take this opportunity to share the little knowledge I do have on a few things."

Ireland Baldwin then goes on to offer advice for her new sister, urging her to always tell the truth and plan to (presumably in the distant future) enjoy her first drink with Ireland.

"You have been born into one crazy family. You are both lucky and cursed at the same time. We are going to have so fun much fun together," wrote Ireland Baldwin.