User blog comment:Xilinoc/Ch. 555 - THE HERO/@comment-9096222-20131031131841/@comment-11051098-20131031202312

Having Bankai is not a demand to become a captain of the Gotei 13. Being able to use Vollständig doesn't have to be a demand to become a Sternritter.

Candice could have been appointed to Sternritter T because she had a potential, and then later learned to use Vollständig.