Robin Thicke and his brother Brennan are taking legal action against their late father Alan

The two siblings - whose mother is Alan's first wife, 'Days of Our Lives' actress Gloria Loring - have filed a petition to "honor the memory of their father, protect his legacy, and prevent his testamentary intentions from being undermined by avarice and overreaching of his third wife, Tanya Callau" now that the Bolivian-born actress is trying to get a larger slice of Alan's estate than the legal documentation states she is entitled to.

The Canadian game show host died in December 2016 at the age of 69 and left each of his three sons - which includes Carter, whose mother is his second wife, 1990 Miss World 1990 Gina Tolleson - equal shares and ownership of his Carpinteria, California ranch, which he bought in 1989 with the intention of it staying in his family forever, 75 per cent of his personal effects and 60 per cent of his remaining estate.

Tanya was bequeathed all of the ranch's furnishings, 25 per cent of his personal effects, a $500,000 life insurance policy, all of his death benefits from pensions and union memberships and 40 per cent of his remaining estate and Alan made provisions that she could remain living at the ranch, on the conditions she paid for the upkeep and maintained the property.

But the 41-year-old actress is now claiming the prenup she signed ahead of their 2005 marriage is now invalid.

'Growing Pains' star Alan's children became the trustees of his estate when his brother Todd declined the role of main trustee, in accordance with changes made to the trust made by Alan in February 2016, and both Brennan and Robin say Callau made no complaints about the prenuptial agreement or the plans for the estate at the time and dispute her claims. They also insist that their father acquired the vast majority of his wealth long before meeting Tanya and is not entitled to more.

In the petition filed on Tuesday (16.05.17) at Los Angeles Superior Court, their attorney Alex Weingarten states: "Now that Alan is dead, Tanya claims there are numerous problems with the Trust and the Prenuptial Agreement. Tanya asserts that there is no chance the 'Prenup' could withstand legal challenge and that she has very significant community rights in the Trust's assets and rights of reimbursement with respect to improvements to the Ranch. Tanya also claims 'Marvin rights' asserting that she had to forego opportunities to pursue and advance her own career in order to support Alan and be his companion and partner, including raising Carter."

Weingarten is also adamant that the trust has made every effort to resolve Tanya's complaint without resorting to court proceedings.

Robin and Brennan have also asked the court for instructions concerning the extent to which the Trust's property is Alan's separate property and whether Tanya waived her community property rights when she inked her name on the prenup.