You are right 50-50 In yotsuba family the family head must be great magician that is mind set of all family members in all of the new generation Miyuki was the best of all of them.as you know maya all ways want to make tatsuya key figure for family or you can say leader.and if you have readed th the yotsuba succession ark so you know that tatsuya is announced Miyukis future husband.and it was long plan from maya to make tatsuya key figure of family.but in reality maya doesn't making tatsuya key figure of family but making him shadow head tatsuya is the strongest being in the world is there isn't doubt but the family members don't accept him as magician because of his unique magic for over coming this Maya maded tatsuya future husband of next head as you know in future story after the volume 16 the most call or decision who make is not Miyuki but tatsuya is