The event will feature never-before-seen performances — some live, some on tape — by Haim, H.E.R., Jhené Aiko and John Legend. (Haim and Aiko are album of the year nominees at the 63rd annual Grammy Awards; H.E.R. is nominated for song of the year. Legend, a Grammy event perennial, is an 11-time Grammy winner.) The event will also include video from the MusiCares vaults of performances at past Person of the Year galas by Stevie Nicks, Usher, Bruce Springsteen, Tom Petty and “one or two artists” who MusiCares won’t name yet. (A photo of Lady Gaga appeared in an online ad on Wednesday, so she’s probably a good bet.) The event will also feature a pre-show DJ set by DJ D-Nice. Laura Segura, MusicCares’ executive director, told Billboard that the decision to make this year’s event a...