Mitch Winehouse, who racked up at least 950,000 pounds ($A1.8 million) in his own legal costs in the failed bid against Naomi Parry and Catriona Gourlay, has been ordered to pay the pair nearly one million pounds ($A1.9 million).
He claimed the women had profited from selling dozens of Ms Winehouse's items at auctions in the US in 2021 and 2023, accusing them of having "deliberately concealed" their sale.
But Judge Sarah Clarke KC threw out the claim earlier this year, finding that he "knew all along" about the intended sale and only afterwards began to pursue them for money in an "aggressive and unpleasant way".
In a judgement on Wednesday, she said: "The claimant chose to bring an inherently weak claim, pursue it aggressively and relentlessly to the end, and make serious and unfounded allegations against the defendants which significantly damaged their reputations, career prospects, financial security and health."
The judge said that, as of April, Ms Parry's costs were estimated to be 715,361 pounds ($A1.4 million) while Ms Gourlay's were 487,132 pounds ($A932,248).
She ordered Mr Winehouse to pay interim payments to each of the women - 569,330 pounds ($A1.1 million) to Ms Parry and 394,521 pounds ($A755,014) to Ms Gourlay - within the next two weeks.
He also must pay the women's legal costs on an indemnity basis, which means those recovering their costs generally get a higher percentage of what they spent than is usual and it is often awarded when one side has behaved particularly unreasonably.
Judge Clarke said that in pursuing his claim, Mr Winehouse had "deliberately turned this case into large-scale and expensive litigation, in circumstances calculated to exert commercial pressure on the defendants to settle on his terms".
He also wanted to expand his claim "very late in the day", which led to the six-day trial in December and January overrunning by three days, while he "actively courted publicity for his serious allegations, including in the press and in court when he knew the press were present".
Judge Clarke said: "This deliberate course of action was undertaken by the claimant with the aim of damaging the defendants' reputations and professional prospects in order to force them to settle the litigation on his terms and pay him the proceeds of sale of their items.
"He did so, knowing that they were vulnerable both financially and in status, and that his public allegations and insinuations of impropriety would only increase their vulnerability.
"The fact that he knowingly and deliberately did this to two young women who had stood faithfully by Amy, and also by him and his family, and who had demonstrated their honesty and integrity over many years, makes his unreasonable conduct particularly serious."
She continued: "I find that the defendants were fully entitled to defend their personal and professional reputations to the end, and that they had no other realistic option given the claimant's serious and damaging allegations, his aggressive conduct throughout, his refusal to accept their explanations, his unrealistic settlement offers and the real risk that he would thereafter be free to continue making public allegations of deceit and dishonesty against them."