Implementing Relationships Between User Roles

I can’t comment on the relationships part but for managing roles you should look at https://github.com/spatie/laravel-permission

your roles appear to be all user to user with an additional pivot value to determine the type

So

User

public function parents(){
	return $this->belongsToMany(User:class, 'user_user', 'user_id', 'related_user_id')->wherePivot('type', 'parent');
}

public function students(){
	return $this->belongsToMany(User:class, 'user_user', 'user_id', 'related_user_id')->wherePivot('type', 'student');
}

public function teachers(){
	return $this->belongsToMany(User:class, 'user_user', 'user_id', 'related_user_id')->wherePivot('type', 'teacher');
}

and by assigning a user with an additional type value you can set whether they are related teachers, parents or students.