My last post has spurred some good discussion and questions...
Jasna asks if Elizabeth Zimmerman's percentage system (well explained in Knitting Without Tears) would have solved this knitter's problem.
The percentage system is a great way to design a sweater from scratch, but it unfortunately wouldn't help in this situation. The first reason is that it is for designing a sweater from scratch - and this knitter's project was half finished -- and the second is that it is limited in the styles that it can help you with... it's all about seamless sweaters (and in their simplest incarnations, seamless raglans).
My heart-broken knitter friend wanted a set-in sleeve cardigan, which although strictly possible with EZ's system, is not the simplest of the versions.
(I may be scorned for this, but... I love EZ's work, but it's not necessarily beginner-friendly, nor is it the solution to every problem.)