Just as old Pablo had said, the Royal Faction's infiltration into mercenary groups was an all-too-common occurrence in this world.
For instance, the Golden Sparrow Mercenary Group of Brittania was originally the "Courage Mercenary Group" of the Welsh. After they grew in size and fame, several high-ranking members were wedded to the Royal Family, which effectively claimed the group for its own.
Similarly, the Steel Cross Mercenary Group of the Holy Solomon Empire was, in fact, controlled by the Hansa Alliance, which was indirectly under the control of the Duke of Saxony. The Duke's family was a matrilineal branch of the Giant Dragon family, meaning that the Steel Cross Mercenary Group ultimately had to obey the will of the Emperor.