If the magic is misdirected, it is possible that the kick-back can manifest in the lives of our family or close friends. I guess this might be so, because the reason that magic works is that we are all connected.
The cleansing/protection work that you are doing ( and letting light into your home is part of that) should help to prevent or at least reduce the occurrence of this kind of problem in the future.
You can share the helpful techniques that worked for you with your siblings.
Or, if they are not open to doing anything, than you can light white candles (tea candles will do) and picture/imagine white light surrounding your siblings, their families, and their homes/property/dwellings. If you can't afford candles, don't worry. Any prayers and/or visualizations for their protection WILL help and benefit them and YOU.
Your love and prayers/visualizations/good thoughts for others are NEVER wasted.
If you do come from a line of Fam trads (family tradition pagans/witches/magicians) that may be why the rest of you feel it when your sister does her workings. The family connections may be extra strong, for that reason.
Don't be afraid to call on your ancestors and the power and wisdom of your family lineage to help you protect both yourself, your immediate family, and your siblings if you are willing.
Wishing you joy, peace, happiness, and protection in this holiday season.
And, since we seem to be living in what the Chinese would refer to as Interesting Times, know that everyone's world is being rocked to its' foundation right now. Since we all are connected, it makes sense that we will feel the ground swells rolling a bit into our own lives. Feeling that energy is NOT a sign of failure of your efforts. (I have to remember this principal in my own life
sigh.
).