So glad you found the forum. It's obvious that you really care about your sister and want to help her get out.
Some posters here have tried to explain to you the importance of using caution and taking proper planning before attempting to try and educate or inform your sister. They do this because you risk being disconnected from by your sister. Once this starts, it's assuredly most difficult to work things out with her. You may not have future opportunities to try and help her again. This is a sad fact about this destructive organization. Your sister is a dedicated scientologist and has been programmed for years to sever ties with anyone or thing that is against Scientology.
Many of us here have been victim to disconnection policies and practices, some have even been the disconnector to our loved ones when we were in. The pain, heartache, effort, and frustrations that come with this were not preventable for some but definately preventable in situations such as yours. How else did Katie Holmes escape? She cautiously planned and executed her safety plan and acted when the time was right. She weighed the consequences of what might happen against based upon what she might or might not do. I gather that this was probably a year long process for her.... knowing that she risked so much if she did not do it right.
Not everyone has the resources or wherewithall Katie Holmes had at her disposal in escaping scientology and it's influence on her family ( her true family). So, my advise is to take time, lay low, don't reveal personlly identifying details ( get a mod to edit your posts if necessary) and plan your strategy by taking notes from some of the comments here and by getting with experienced and knowledgeable commenters by PM and be patient. You don't want your sister disconnecting from you and if you act with haste, as many have seen before, this could very well happen.
Best wishes to you and your family,