Lady A,
I'll definately pray for your sister and your whole family. As Silverheels says so well, Lightfoot fan prayers are mighty powerful
. I think it is in part due to the fact that so many of them from my experience are wonderful "Rainy Day People". Good-hearted people just seem drawn to his music and powerful lyrics.
It is good to pray for others' medical needs while in the midst of our own in my family, as it reminds me that there are others at any given time out there in pain or duress too; getting through their difficulties medically or otherwise, and helps me to dwell less on mine and my wife's, and remind us we are not alone, just as neither are your sis nor you.
Your sis, family, and you sure have my prayers in mind and heart, and hang in there to the both of you. My experiences over the last ten years are that there is in fact light at the end of every tunnel I've seen medically, and I am sure with prayers and positive thinking your sister will find hers as well.
Cheer up if you can, and remember as many above have said; don't hesitate to post more or PM about this to those who speak to you in their words; this group really does care about one another, and that includes your sister and you !
Thoughts and Prayers,
geo Steve