I wonder if old Soldats kept Noir 'spares'

Considering how hazardous the job of an assassin is, I wonder if the old Soldats from centuries ago, when it was customary to have Noir as a unit of 2 lady killers, kept any "spares" for when one of the 2 got killed? Plus, I wonder what would have happened if the Soldats had not asked Mireille to infiltrate the manor and kill one of the other 2 candidates, and Chloe and Kirika completed the accession and became the new Noir? Would they have been ordered to go after Mireille, or maybe Mireille would have become a "spare"? (But then I kind of doubt Mireille would be willing to be a "spare" for the Soldats.)