You cannot change something "a little" and call it your own.
If you can still recognize any part of it as someone elses,
then it is still not your design. You must change it so it
is not recognizable at all from the original design.
I'm a tole painter and I use several artists designs. 99% of
the artists tell you you can use their patterns for fun or
profit, but it may not be reproduced by a manufacturer. I
assume this applies to copyrighted quilt patterns also. I also
personally think its a little hard to copyright a quilt square
that was created back in the 1800's or earlier. Just changing
its name does not make it yours.
You cannot copyright ideas or concepts unless you have used
them yourself to create something. Does that make sense??
Catlady