So yeah. Here is the thing about VOCALOIDS that a lot of people tend to ignore.
First off, there is no relationship, even sibling wise. If you really think about it they have no personalities at all, they’re just art for boxes. They can literally be anything you want them to be cause nothing about them is canon. Depending on whatever song it is, they have different personalities, relationships and pasts. So nothing is really set in stone. Only real thing that is set in stone is there name, ages and birthdays. He could be a child molester if the song says he is. Just saying. All they all are are box art.