I've found one of my standard ways of working is to start from a pattern, and make many changes so it fits me and has flattering proportions for my body. Now I've made so many changes I wonder if it counts as the same pattern. Would the original designer be aggrieved if I didn't mention her, or insulted if I did
Last year I did a lot of work on a casual pullover top. Added darts, changed the shape of armhole and sleeve cap so they fitted well, changed to a more flattering neckline for me. The only thing unchanged was the parallel sides of the body ! I had made so many changes I decided it had become one of the large family of slightly drop shoulder loose fitting top patterns, and I needn't mention the original designer.
Recently I've been working on a knit tee. I didn't notice when choosing the pattern that it is close fitting, and I don't like wearing close fit knits. In fact the hips even have negative ease, the last place I need tight fabric. The sleeves are so tight I couldn't bend my arms, and the neckline was too small for my head. I debated whether to use another pattern, but this has 2-piece raglan sleeves - a seam along top of sleeve. Which make it possible to get a good fit over the shoulders without all the strain and drag lines at the armhole of a 1-piece raglan sleeve. Now I've changed nearly everything about the pattern except the armhole seam shapes. It does still have the original general style elements : raglan 2-piece sleeve, near jewel neck. But it is now a loose fitting top, not a close fitting one. A different spirit. So I wonder if the designer would be peeved to be linked with it, if I said 'derived from' or 'inspired by'.
In a sense I'm doing what a designer does when they develop a new style.
What do you do about giving credit for the pattern in these circumstances ?