Bobbi Kristina Brown
Bobbi Kristina was the sole heir of her mother Whitney Houston's fortuneGetty

Bobby Brown has reportedly opened an application to gain guardianship over his daughter Bobbi Kristina, who remains unresponsive in hospital.

According to the Atlanta Journal-Constitution (AJC), the r'n'b star and the 22-year-old's grandmother Cissy Houston both marked their attendance on Thursday (7 May) at the DeKalb County Courthouse.

The move will mean that Brown could take full control of Bobbi Kristina's $20m (£12.9m) estate, which was handed to her in 2012 as the sole heir of her mother Whitney Houston's fortune. But Houston has allegedly responded to Brown's bid by stating her plans to contest him.

According to Radar Online, a family source said: "Cissy Houston will fight this to the grave. Since day one, all of the Houstons have been waiting for Bobby to try and get Bobbi Kristina's money and they knew it was just a matter of time. No one is surprised that he is making a grab for her money."

But Steve Worrall, an estate planning attorney, told AJC that even if Brown is granted the guardianship, it would not bring any changes to the will, which stipulates that in the event of Bobbi Kristina's death, Cissy, aunt Pat Houston and uncle Gary Houston inherit her assets.

"It would be appropriate for him to apply for guardianship, conservatorship or both. Once [Brown] is appointed as guardian he would have the authority to handle her person. A conservator would have the authority to make financial decisions. Certainly somebody needs to handle her financial affairs," Worrall said, according to AJC.

Bobbi Kristina has been in hospital since 31 January after she was found unconscious in a bathtub at her home in Roswell, Georgia. The incident happened before the third anniversary of her mother Whitney Houston's death, who died on 11 February 2012 in similar circumstances.

In April, Brown stunned fans when he claimed that Bobbi Kristina was "awake", telling the crowd at concert in Texas: "I can say today: Bobbi is awake. She's watching me."

But in a statement released to People Magazine, Houston shattered any hope of a full recovery by revealing that doctors said she had "irreversible brain damage".

"I have just returned from visiting my granddaughter Bobbi Kristina in the hospital and while she is no longer in a medically induced coma she has a tracheotomy and according to the doctors she has global and irreversible brain damage and remains unresponsive."