To answer the decade old question, yes, I can disregard Leia as Luke’s sister, for the simple reason that there’s no real proof that they’re related. Ben merely says ‘Your insight serves you well’ in response to Luke’s intuition. He’s already known to lie when it serves his purposes, so he could merely have been allowing Luke to believe that Leia was his sister to make sure that the real twin stayed ‘safely anonymous’.
The hint of Leia’s Force sensitivity only appeared after Luke basically said that she should be terrifyingly powerful with the Force, and this tracks in my mind to how the Force should really work - if you believe in it, you can become strong in it. Even The Force Awakens doesn’t ruin this idea, since she would have had 30 years to develop some real Force ability and Ben junior would have grown up believing that he was destined for greatness.
There you go. ^^^^^^^^^^^^^^This.