So, you would be in the clear to make the pattern and then sell it to her? At that point, what difference would it make if you shared? The designer isn't going to make any more money either way.
It seems that if we are so concerned about designers getting their cut (and we should be so they can keep designing), we should all agree that we won't sell used patterns.
Just realizing the loopholes in copyright laws - I've never really thought about it before.