But this wasn't the first time these two have sat down to write a song together. In fact, Jamie Lynn said they talk music quite frequently.
"Whether it's listening to some of her tracks or it's me playing the guitar or playing the piano or just us messing around as sisters, we've written some really stupid, silly songs," Jamie Lynn told MTV News earlier this month. "It's really just so fun when you have someone who appreciates the writing process and you're so comfortable with. We've never finished anything ... but we do start."
Somehow, in between their busy schedules and with Jamie Lynn's 5-year-old daughter Maddie dancing in the studio, they did manage to find time to lay down the vocals for the mid-tempo track "Chillin' With You."
"She was like, 'Why don't we try singing this together?' and I got in there and I literally sang it four or five times and it turned out really cool and we loved it,"Jamie Lynn said. "As sisters it's just fun to do something like that — it was just a really natural, organic thing."
Jamie Lynn is now branching out on her own, releasing her brand-new country ballad, "How Could I Want More," and working hard on her debut album. Earlier this month, Britney revealed that it "would be cool" to go country for Jamie Lynn, so how would Jamie Lynn feel about teaming up with her sister once again?
"I would love it," the singer said, adding that Britney has given her the "confidence" to release new music. "I think it would be cool for her to switch it up, and obviously just for me to do another song with my sister, I would be totally open to that."