Bollywood-loving ’90s kids will have the chance to relive their heyday next month at an arena-sized Throwback ’90s event featuring three legendary playback singers. The heavy trio of Udit Narayan, Kumar Sanu and Alka Yagnik appeared onstage together for a song this summer on the reality show Superstar Singer, and the chemistry must have been still there because the three are now playing a run of shows in North America this fall.