You have to decide this on your own.
Nobody knows, where you live, with who you live, what your relationship to your sister is, how mich influence she has in your life etc.
Just adding my own experience, I admired my cousin, we were more like brothers, esch of us liked the other very much. We did everything together, had a very similar mindset. Then I told him about ToZ and that I am a Zevist. BIG REGRET. However, shortly after I told him about, maybe the same day, my mother told me that his grandma is jewish. And I was like oh my shit, what have I done.
And yea after a few days, maybe 2-3 we met (he red some of the ToZ Webpages) and he basically reacted like a jew would.
He doesn’t hate me, I don’t hate him.
I just do not do anything with him now. Reason, if he doesn’t respect Father Satan, I do not want to be around him.
But yeah, he is a jew. It will be a different story with your sister I guess.
My point is, this kind of stuff can destroy relationships... on the other hand.. It can really empower relationships aswell. But the mist important thing here is your own safety