Dwina Gibb, Robin Gibb’s widow, fears the mother of his love child fathered with their former housekeeper will demand more cash since his death – despite reportedly receiving a £4 million ($6.4 million) pay off.

After 12 months of legal wrangling Robin Gibb’s lover Claire Yang is said to have received the one off payment for three-year-old Snow Robin’s care.

But after Robin Gibb’s death the family are said to fear his former lover will demand a larger slice of his £140million ($225 million) fortune.

Dwina Gibb is said to be worried Claire Yang, 36, will seek legal advice despite agreeing to the one-off child maintenance deal in January.

A source close to the Gibb family told The Sunday Mirror the legal fight, which went on while Robin was undergoing hospital treatment, upset Dwina.

The source added: “If Claire does go to the funeral she will be ¬keeping her distance from Dwina and it will be awkward. Robin never walked away from his responsibilities and always made sure the child was fully provided for.

“Snow Robin is a Gibb child so will be treated exactly the same as the other three children. It is not about the money but it is the nature of the lengthy legal process which distressed Dwina and the family.”

After 12 months of legal wrangling Robin Gibb's lover Claire Yang is said to have received the one off payment for three-year-old Snow Robin's care

Robin Gibb, 62, who died from liver and colon cancer on May 20, had a long-term affair with Claire Yang but was asked to leave the Gibbs’ house by bisexual Dwina Gibb, 59, when she became pregnant.

Despite having an open relationship it is thought Dwina Gibb “hit the roof” when she discovered Claire Yang was pregnant.

Robin Gibb later brought his mistress a home five miles from his Thame home after paying her rent before his daughter was born.

Friends have spoken of Claire Yang’s love for Robin Gibb and the former housekeeper, who became known as the star’s companion, thought the pair could have a future together.

But Robin Gibb is thought to have told his mistress he would never leave his wife.

Speaking about her married life, Dwina Gibb famously said: “We have an open relationship. Robin has had flings in the past with friends of mine and he talks about them.

“It doesn’t worry me because I trust my friends. And I am, after all, his best friend as well as his wife and lover – and I’m sure we’ll be together.”

Robin Gibb and his twin brother Maurice formed the Bee Gees with their older brother Barry, now 63 in the late 50s.

The trio shot to mega-stardom after creating the soundtrack to Saturday Night Fever in 1977. Maurice Gibb died of a burst intestine in 2003 and their younger brother Andy died from a cocaine overdose aged just 30 in the 1980s.

Under the Inheritance (Provision for Family and Dependents) Act 1975, any child in UK is allowed to contest a will.