Gerrick Kennedy, music writer for the LA Times, took to Twitter earlier this evening to seemingly confirm the rumours, adding that Mary Lambert is also likely to appear onstage, meaning Macklemore and co will be performing their anthem Same Love. (Source)
WGB: They are exactly who I had hoped she would perform with when I heard she was going to make a Grammy's appearance. I know many of you messaged me that you wanted to see her do a Beyonce duet or Katy Perry duet. I wasn't excited to see that. I think "Same Love" and Macklemore fit her energy and vibe.