I always read the copyright BEFORE I buy any pattern or book.... and never buy any with copyright that is restrictive--can't sell items at craft fairs, etc.... Another set of patterns to avoid are the Atkinson's.... can't make and sell these either....
If your pattern came from somebody else's pattern you saw it is still theirs--is the way I understand it. The IDEA came from 'their hard work....' or that is the way I understand it...