If there were actually a bride on Vampire Weekend’s new album Father of the Bride, it would probably be Danielle Haim. The singer, guitarist, and middle child of indie rock sister trio Haim joins Ezra Koenig for three songs on his band’s fourth record. She’s a surprising yet familiar presence: surprising because she’s the first person other than Koenig to sing lead across a Vampire Weekend album, familiar since the rueful, sunlit nostalgia of Father of the Bride isn’t so far from the Haim sisters’ moody, California-inspired pop.

“I know the reason why you think I oughta stay/Funny how you’re telling me on my wedding day,” Haim sings on album opener “Hold You Now,” the first of three country-tinged duets that trace a faltering relationship from doubt to renewed commitment. Together, the songs offer an emotional link across a sprawling album—a spiritual cushion against recurring disillusionments, a modern take on Loretta Lynn and Conway Twitty duets.

Like 2013’s Modern Vampires of the City, the bulk of Father of the Bride was produced with Ariel Rechtshaid, the celebrated indie and pop producer who’s also Haim’s live-in romantic partner. “There were always people coming in and out [of Rechtshaid’s home studio],” says Haim. “Ezra was very into collaboration and asking for people’s ideas.” The album also incorporates the mellow funk of fellow Californian Steve Lacy, who sings on “Sunflower” and “Flower Moon,” and producer credits for DJ Dahi and BloodPop.

Calling during a car ride with sisters Este and Alana, Danielle spoke about her first run-in with Koenig, the organic studio process for Father of the Bride, and how she recently found herself serenading Jenny Lewis with Rilo Kiley songs.

Pitchfork: How did you get involved with Father of the Bride?

Danielle Haim: I’ve known Ezra for so long. I actually met him when I was on tour with Julian Casablancas in 2010, I think the festival was Super Bock Super Rock in Portugal. I was a big fan, so I remember coming up to them backstage being like, “Hi! So nice to meet you”—and they were super nice. Through the years we’ve run into each other. Of course, Ariel helped produce their last album, and Ariel’s my partner, so that made us closer. When [Ezra] started talking about his new album, he showed me, I think it was, “Hold You Now.” He was like, “Maybe it should be like a duet,” and I was like, “Oh my god, anything I can help with, I’m so down.” That was the first song we officially started working together on.

It feels like you’re not just a voice on this album, you’re a little more like a character. Could you talk about how you took on this role?

I don’t personally see it that way. [Ezra] was always harkening back to these old songs that he loved growing up—duets between a male and a female. We wanted to capture that same spark. But it was such an off-the-cuff, loose thing. They were working a lot at my house, actually. Ariel has a studio there, and I would come in to say what up, and Ezra would be like, “Hey, listen to what I wrote, do you want to put some harmonies on it?”

I did not realize they were working at your house. What’s the vibe in there? Were you doing anything special, hosting-wise?

No. I wish I was more like that, like, “Hey, do you want anything to eat?” I wasn’t really a great host. When Ariel and Ezra start working, they’re in the zone. I never really wanted to bother them. It’s not in my house—there’s a separate studio, it’s not like it’s in my living room so I wake up and I’m right there [laughs]. But it was easy—if I was like hearing something cool, I’d be like, “Whoa, this sounds dope.”