I have a similar question/situation
My friend and I were strolling around a craft fair around christmas time and we noticed some knit toys. My friend was convinced that the underlying structure of the toys were from a pattern that she created and sold on etsy. She stated that items made from that pattern were not for resale etc. However the seller had made some variations of the toys by changing the style of teeth/hair and made the arms longer etc.
I let my friend rant about it for several weeks.
Does that constitute as copywrite infringement? I have no idea - I just comforted her as much as any friend could. Any insight would be appreciated, maybe I can tell her something to put her mind at ease, whether it is what she wants to hear or not