Not to insult your sister, but there are no "Quilt Police" who have absolute say in what is or is not a good design, or a creative design. Simply because she has different ideas, DOES NOT mean that they are better, just different. If you have an idea in mind, JUST GO FOR IT GIRL, and I'm sure you will be pleasantly surprised at the results. Put her comments aside and follow through on your original idea, then won't she be surprised when it becomes a beautiful quilt, all your own design? If this happens again, just thank your sister for her suggestions and tell her you will think about it, then do it your way - what comes from your heart. I'm sure your quilt will be beautiful.