Thank you for agreeing to at least pass on my concerns to my sister. Please let her know I’m just being a concerned uncle.
I continue to believe she has the best intentions for her children. However, I have also described the ideology of the organisation whose materials she is teaching, as racist, bigoted, fundamentalist, anti-scientific propaganda, all of which I firmly stand by. I have thoroughly researched the course material and Bob Jones University, the fundamentalist organisation behind them and heard from past students of similar courses (such as Jonny Scaramanga) who suffered later in life because of these courses.
If you need more evidence then maybe you can read a few examples of the lies from A Beka books, published in Mother Jones Magazine, or watch for a short video on the bigotry in homeschooling materials.
Your grandchildren deserve a normal, non-religious education and exposure to children from all backgrounds. Your assurances that right now they are doing fine cannot be used as an excuse for complacency!