So very sorry for your loss. I have never had a sister, and only one brother, we are so very close. I know your loss is very hard, especially going through her stash.
I have all of my mother's things, including her sewing machine. She was an avid crocheter, I have all of her patterns, needles and many things she made, only a few she had started and never finished. I also crochet, but couldn't do any myself for many years after mother passed, as I would think of her when I would start and have to put it all away.I had such a rough time, trying to complete one of her afghans, all blocks and pattern were there, but I just had to have a dear friend complete it for me. My mother passed 23 years ago and I still have problems when I come across her patterns or needles I have kept. I can't bear to give any of them up, I keep thinking I will give a few to a family member who also crochets, I will someday maybe. Wishfully hoping that my daughter will want them, but even though she has dibbled in crochet, she is not at all a crafter. She would only want them for sentimental reasons, and there are so many, probably 50 or 60 needles.
I am sure there were many tears while washing, ironing and talking to her, and more in the future, but you have to know she will always be with you when you are working on any project that involves any of her stash. How sweet of your neice to give it all to you. What a nice gesture on your part to complete the yo yo quilt for your neice. I am seeing a beautiful memory quilt from some of her stash in your future. Just remember that she would be so happy knowing you are using her stash and what memories she would have shared. Take care and show us some of your projects you make. May God's Blessings be with you and your family in this loss. Prayers are with you as well. What a wonderful story you have posted, but your feet will only hurt for a short while, and your memories and love will last forever.