The long-running dispute has seen Ms Rooney, 35, accuse Rebekah Vardy, 39, of leaking "false stories" about her private life to the press in October 2019, after carrying out a months-long "sting operation" which went viral around the world.
Ms Vardy, who is married to the Leicester City striker Jamie, denies the accusations and is suing Ms Rooney, the wife of ex-England player Wayne Rooney, for libel.
At a preliminary hearing on Wednesday, the High Court heard both women will be using experts to analyse the Instagram data on relevant devices ahead of the trial, which is likely to commence in full next year.
Representing Ms Vardy, Sara Mansoori said her legal team was “taking steps” to make the third-party Instagram data available for the court and denied any secrecy.
She continued: “There is no difference in approach in terms of what Mrs Vardy is expecting and what she is prepared to provide.”
Judge Roger Eastman concluded that the Instagram experts should be granted access to data from other devices that had used Ms Vardy’s account, which may include her husband’s phone or computer.
The court previously heard that other people had accessed Ms Vardy’s Instagram account, including her assistant Caroline Watt, Mr Vardy and his social media manager.
Judge Eastman said: “In order for the expert to explore what has gone on … they need to have access to more than just the personal devices of Mrs Vardy and Mrs Rooney.
“The outreach and depth with which Instagram matters circulate, and can be circulated, is rather wider than that.”
The judge continued: “That may well involve access to other people’s devices, rather than just Ms Rooney and Ms Vardy’s devices.
“In light of the fact Ms Vardy has given access (to her Instagram) to Ms Watt and her husband, it seems to me at least they and their devices are, for the purposes of disclosure, within her possession and control.
“Whether Ms Mansoori likes it or not, for the purpose of instructing the experts … their devices are up for grabs for inspection and analysis by the experts.”