You are making the quilt - you can make it / change it / redo it in any way you want. The problem arises if you try to resell a pattern that you have altered (the pattern not the quilt!). Copyright laws are designed to protect the product - meaning the pattern and pattern maker. It is a very grey area concerning making items from a pattern and selling them. You may not sell the patterns without permission, but selling items from a pattern are not going to cause problems unless you are doing it on a massive manufacturing scale. It is good form and karma to give credit to the designer if you are selling an item made from a particular pattern. I find that buyers at an event appreciate having that information. Another way to think about it is if I am selling gift baskets and one of the items in that basket is a small bottle of lotion, the company making the lotion is not going to sue me for including their lotion. They will think of it as advertising their product.