Cant move my sub-task on Rapid Board if I am not the owner of this task

Lets assume, I have a list of tasks: "task1, task2, subtask-of-task3", so I'm not an owner of task3, only it's subtask "subtask-of-task3".
http://crazypanda.ru/v/clip2net/e/L/EGrfCHVkIc.png
In this situation it is impossible to sort tasks in rapid board. How we are supposed to do in this case?