Myer and David Jones are forcing each other to release confidential information, including highly sensitive supply agreements and potentially embarrassing internal memos, as they prepare for the trial between Myer and designer Kym Ellery.
Myer dragged David Jones into proceedings a few weeks ago by requesting copies of its supply agreements with 22 designers, including Akira, Collette Dinnigan and Zimmerman.
But at a hearing in the Victorian Supreme Court on Friday before Justice Michael Sifris, barrister for Myer, Peter Murdoch QC, said the documents received from David Jones were excessively redacted and it was impossible to see any relevant information.
Myer was also now seeking access to any legal advice Ms Ellery received before her decision to defect from Myer to David Jones mid-way through an exclusivity agreement.
It also wants copies of her new supply agreement and any files notes or internal correspondence written by David Jones staff about Ms Ellery.
Meanwhile, barrister for the label Ellery and Ms Ellery - and also representing David Jones on the matter of subpoenas - Charles Shaw, said his clients need access to internal Myer correspondence about how Ms Ellery might be treated if she were forced to return to Myer, and evidence of how valuable Ellery was to Myer's business.
Both parties have objected to disclosing certain documents and asked Justice Sifris to decide which must be produced. He reserved his decision until Tuesday.
Myer launched legal action against Ms Ellery and her label in January seeking an injunction preventing her from supplying David Jones and forcing her to fulfil a delivery to Myer.
However, it dropped that injunction shortly before David Jones' 2013 fashion launch, which featured her label, and was now pursuing her for damages and breach of contract.
A trial was due to start on April 15, although both parties have pushed for an earlier date.
Justice Sifris said there was no space in the Supreme Court's workload for an earlier trial.