I'm not including Valt, Daigo and Rantaro because they already have siblings.
Wakiya
- doesn't care. Let's Hoji take care of them while he practices in another room
Shu
- thought them how to Beyblade and lets them practice with him in the beypark.
Ken
- comes and watch his puppet shows and even help him create puppets
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Lui: LEAVE ME ALONE GO TO THE OTHER ROOM!!!!
Siblings: Why?
Lui: BECAUSE YOUR INTERRUPTING MY TRAINING!!!
Siblings:........ Why?
Lui: *TRIGGERED*
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Zac
- let's them sing with him in his concerts. And plays with Akira
Xander
- teach them stuff inside the dojo
Free
- sleeps with them.