Bobby Brown has reportedly filed for guardianship over Bobbi Kristina Brown's estate.

The 46-year-old singer is believed to have submitted documents to request he controls the estate left to his 22-year-old daughter when her mother Whitney Houston passed away in 2012, 11Alive reports.

Bobbi is currently being treated in a medical rehabilitation centre after being found unresponsive in a bathtub on January 31.

Meanwhile, Bobby's lawyer previously confirmed that doctors are currently unsure what kind of ''quality'' of life Bobbi Kristina will have.

In a statement, Christopher Brown said: ''Bobbi Kristina's condition has changed since moving from Emory University Hospital and there has been improvement. Doctors have indicated that she will have a long life.

''However, Bobbi Kristina is presently embarking on a rehabilitation process and the quality of her life will not be known for years to come.''

Whilst Bobby simply added: ''We thank everyone that supports Bobbi Kristina and God is hearing our prayers.''

Grandmother Cissy Houston has admitted she is praying for a ''miracle''.

She said: ''Meeting with the doctors and understanding that she can live in this condition for a lifetime truly saddens me. We can only trust in God for a miracle at this time. Keep us in your prayers.''