Two of Johnny Hallyday’s children are to contest the French rock star’s will as simmering family tensions threatened to boil over after he left his entire fortune and all his artistic rights to his fourth wife, Laeticia, 32 years his junior.

Lawyers acting for Laura Smet, 34, and her half-brother, David Hallyday, 51, said the will drawn up by the man dubbed “the French Elvis”, whose death in December plunged France into days of national mourning, was “manifestly in contravention of the requirements of French law”.

Smet, whose mother is the actress Nathalie Baye, was “stupefied and hurt” after learning that she and David – Hallyday’s only two biological children – had been written out of their father’s will, the lawyers said, adding that the document had been drawn up in California, where the singer spent much of his time in later life.

In a searing open letter to the French news agency AFP, Smet also hinted at mounting antagonism between the family members, suggesting that she had been prevented by Laeticia, a 42-year-old former model, from meeting openly with her father – and even from saying goodbye to him before he died of lung cancer, aged 74.

“Dear Papa, it’s two months since you left,” she wrote. “I miss you so much, and at the same time I have never felt you so close to me. I learned a few days ago that you wrote a will completely disinheriting David and I. It was only a few weeks ago that we were eating together and you said to me: ‘So when are you going to have a child?’

“But what can I pass on to that child about you, someone I’ve admired so much? … So many questions without answers. So many times we had to hide to see or call each other. I cannot bear not having been able to say goodbye to you papa, do you know that, at least? … (But) I hear you, papa, and I have decided to fight. I would have preferred it if this could have stayed in the family, but unfortunately that’s the way our family is.”

A widow does not automatically inherit all of her husband’s estate under French law, and is generally obliged to share part of it with his children. Hallyday’s will stipulated that should Laeticia, 42, die, all his property and rights should pass to Jade and Joy, the daughters he adopted in Vietnam with Laeticia.

In a statement to the AFP, Smet’s lawyers said she had been left with “no material goods, no rights to his artistic work, no souvenir, no guitar, not even the signed sleeve of the song Laura, which is dedicated to her … When one is a child, one has the right to receive something from one’s father.”

Hallyday, born Jean-Philippe Smet, sold more than 110m records and was seen live by an estimated 28 million people in a career that lasted more than half a century. His recordings went gold 40 times and platinum 22 times in France, but sold barely a copy abroad. Hundreds of thousands of fans lined the streets of Paris for his funeral, when the French president, Emmanuel Macron, described him as a “national hero”.