When is a copy not a copy?

[Soph2]

Does anyone knowwhat the reproduction laws are surrounding modifying pattterns (ie: for clothing or pattern for knitting). If one were to modify a design at what point would it be your design and not a copy?

[Gmcd01]

I'm afraid there are no hard and fast rules because every case can be so different. Copyright law looks at whether the part taken is 'substantial' in volume and similarity. Trademark law will look at oral, aural or conceptual similarity (e.g. a copy of the same theme).
Registered design law is something I really can't explain over Answerbank sorry!
Your question really can't be answered without seeing the designs in situ- and even then it comes down to evidence and a judge's opinion. Sorry that's not more help.