User blog comment:Linathan/Unit Spotlight: Maestro Goddess Miku/@comment-26455864-20150904045153/@comment-26140304-20150904125813

Good luck! :D

Actually, the cap only applies to Leader Skill/Extra Skill/Spheres. The three categories can stack, but it caps out at 10 BC. Since BB/SBB buffs are separate from those three, you can surpass the cap.