Tadase's Family Tree.

In Spanish we have to do a family 나무, 트리 and I decided to do Tadase Hotori's family (Shugo Chara). I was wonder what family members he has and would Ikuto and Utau be considered his step-siblings? Also I can't find a good picture of his Father 또는 Grandmother. Thank 당신 all in advance for the help! ^-^