According to Rap-Up they're joining Bey on stage for a medley of DC hits, finishing with "Nuclear"

And as the encore of the show, Bey will perform the new song


Quote:
Beyoncé will open the show solo, bringing out Kelly and Michelle midway into her set for a brief medley of the group’s greatest hits, ending with their new song “Nuclear.” The Pharrell-produced track, their first original material since 2004, appears on their career-spanning compilation Love Songs, due January 29.
Beyoncé will take the field again for the finale, which is said to include the debut of a track off her upcoming fifth album.
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