Alan Jackson’s eldest daughter, Mattie, welcomed her first child into the world on June 20 and the country star just shared a photo of the family with the newest addition with fans. While the initial post came from the new mom, the proud grandfather also took to social media to share the baby news. “Denise and I are so happy to announce the arrival of our grandson Wesley Alan Smith,” Jackson writes. This is the couple’s second grandchild, and the comment section of the post was full of love and congratulations. “Those little bitty things… Congratulations to the whole family,” one fan writes! M…