Natalie,
I think that, legally, you are correct that we can use whatever fabric we bought legally in our quilts & can even sell those quilts (
http://info.legalzoom.com/can-make-i...ric-21253.html) Unfortunately, not every lawyer is honest, and even those that are have an obligation to zealously represent their client's interest which can make for quite a headache.
Of course, the design for quilts is a totally separate issue. If there's no pattern (i.e., you saw the actual quilt at a show) then you really do need to get permission to make a very similar quilt, unless the design is either in Public Domain or copyleft. If there is a pattern, it's anyone's guess. Seems like something as simple as making quilts should not be shrouded in so much complexity. I'm glad for copyrights since I believe it fosters new & innovative designs, but all the legal stuff is just plain frustrating!