Dan Smyers and Shay Mooney of Dan + Shay — and their wives — were guests at Justin Bieber's second wedding to Hailey Baldwin over the weekend.

It may seem odd that the country duo attended Bieber and Baldwin's exclusive and private affair, however they've actually been friends with the pop singer and his television host wife for some time now. The newlyweds friends-and-family-only ceremony took place in Bluffton, S.C., on Monday (Sept. 30) and included a number of celebrity guests, including Bieber and Dan + Shay's shared manager, Scooter Braun (Braun is the head of SB Projects and now owns Big Machine Label Group).

Bieber and Dan + Shay were first spotted together onstage at Austin's historic SXSW Music Festival in 2014. Bieber urged his followers to vote for the duo ahead of the 2015 ACM Awards, saying: "Love an underdog. Got to write with these guys last year. Good people." The same year, Dan + Shay made a video and jingle to promote Bieber's Purpose album.

Then, in 2016, Smyers and Mooney saw Bieber's concert in Toronto and documented the experience on social media. Bieber, Smyers and Mooney since have had several exchanges promoting each other's music and asking to write with one another via Twitter. The gents even suggested a three-part harmony on Rascal Flatts' next jam session!

See More Pictures From Justin Bieber and Hailey Baldwin's Wedding: