Enrique, I am so sorry to tell you that you cannot do that. Under the new privacy rules that WikiTree was forced to adopt to be in compliance with the GDPR, you can only enter your own DNA results. You would have to invite each of your siblings to join WikiTree and then they could each enter their own results.
It's easy to invite them - just edit the person's profile and enter his/her email address. An invitation will automatically be sent to the person and all they have to do is click on a link in the message to accept the invitation. They don't ever have to do anything else here after that, although your purpose is for them to enter their DNA information.