Little Big Town has been going strong for more than 25 years, and Kimberly Schlapman thinks she's figured out the recipe for their success - as well as the reason her bandmates' relationship is so strong. "I make a joke that I am the secret to [Karen and Jimi's] marriage because I'm always in the middle of them," Schlapman, 56, exclusively told Us Weekly while discussing her partnership with AbbVie's Changing the Tune on Parkinson's Disease campaign. "They have a great relationship, a beautiful family. We've all been blessed.