But they say they left behind an outstanding collection of artefacts, including rare silver snuff boxes, Elizabethan tankards and old master paintings.
There are over 300 items claimed by Manny and Brigitta, including part of an "exceptional" £13m ($23m) silver collection which Manny began building up in the 1980s.
The couple want the valuables returned to them - while Maxine, 57, and Gerald, 55, are "counter-suing" for a further 180 items, including £3m ($5.3m) worth of jewellery.
The total value of the objects at stake is around £17m ($30m).
Lyegrove House, a sprawling Jacobean mansion set in 18 acres of lush Gloucestershire country, was bought by Maxine and Gerald in 1993 - although their parents say the cash came from "income distributed to them from trusts settled by their parents".
The house neighbours Prince Charles' estate at Highgrove.
Manny and Brigitta say that all the family viewed Lyegrove as the older generation's country home, and that they "ran the house".
But their children insist it was bought as a weekend retreat for all of them.
In 2011 the couple relocated to Monaco on the "clear understanding" that they could return to Lyegrove whenever they came back to England, they claim.
That remained their belief until they were "excluded from the house by their children in 2015", said Rubin.
The family rift has its origins in two trusts settled by the parents in 1967 - with their children named as the "principal beneficiaries".
The basis of this claim is either that the children paid for the jewellery, or that Brigitta gave it to Maxine under an alleged deed of gift, or by orally expressed gifts.
Most of the family's £600m ($1070m) fortune is contained in the trusts, and Maxine and Gerald's children are "the next generation of likely beneficiaries".
Giles Richardson QC, for the siblings, explained that family relations "broke down" in 2011, prompting two earlier legal disputes about the trusts which were ultimately settled in favour of Maxine and Gerald.
But the family are now at loggerheads again over nearly 600 items, with the dispute set for a full blown trial at the High Court from April 25 onwards.
The "most significant aspect" of the siblings' case is Maxine's claim for "delivery up" of the jewellery collection, said Rubin.
"Worn by Brigitta for many years", the jewels are valued at £3m ($5.3m), and include an exquisite sapphire ring.
"The basis of this claim is either that the children paid for the jewellery, or that Brigitta gave it to Maxine under an alleged deed of gift, or by orally expressed gifts," explained Rubin.
However, Brigitta is disputing her daughter's claim to the jewels, added the QC, and "denies that she made any lifetime gifts at all".
Maxine and Gerald also allege their parents removed art and antiques from their home in the south of France after the "breakdown in relations"- moving them to their apartments in Paris or Monaco.
On top of that, they are demanding that their parents account "for the use of (their children's) funds in various bank accounts over the last 40 years".
Manny is a self-made millionaire who set up Asda Property Holdings in the 1960's, having left school aged 14.
He has spoken in the past of his regret at setting up the trust funds for his children when he was worried about inheritance tax.
Maxine is a freelance art consultant and mother-of-two, while Gerald is a successful businessman who once worked alongside his father.
He lives in a large house near Hampstead and has a passion for flying helicopters and collecting Aston Martins.
