Bobbi Kristina Brown claims Whitney Houston wanted her to marry Nick Gordon.

The late 'I Will Always Love You' singer's daughter announced she had secretly married her fiancé earlier this month, and says her mother - who died of accidental drowning in 2012 - would have supported the union, even though Nick was raised as her stepbrother.

Speaking on US TV's 'Extra', Bobbi, 20, said: ''She wanted this. This is something she wanted to see.''

Nick added: ''[Whitney] just treated me like she gave birth to me. She treated me like a son. She made me promise several times to look after Krissy ... and Mom, I will never, ever, ever break that promise.''

Nick, now in his 20s, was taken in by Whitney when his mother could no longer care for him, before he was a teenager. He was never officially adopted by the star and he and Bobbi - whose father is singer Bobby Brown - have no blood relatives.

Nick explained: ''Me calling [Whitney] mom, this where everybody gets the ['brother and sister' thing from].

''We were young. Krissy looked at me as an older brother, and I looked at her as a little sister.''

Romance between the pair blossomed after Whitney's death, and the couple claim negative reaction to their relationship only made them stronger.

Bobbi Kristina said: ''It lit a fire up under our ass and we went hauling.'' Nick added: ''The critics can say whatever they want to say ... it's like we have a force field and that s**t's just bouncing off of it.''