During Maren Morris’ sold-out show at Nashville’s Ryman Auditorium on March 13, Miranda Lambert, Cassadee Pope, Brandi Carlile and Natalie Hemby surprised Maren by joining her onstage to sing “My Church.” “This moment was not planned but it made my đź–¤ explode,” said Maren, in part, via Twitter. Earlier in the evening, Brandi teamed with…