Oasis "will die" before they split up.
The band sparked rumours they were set to break after they were forced to pull out of the second night of the Virgin Media V Festival when singer Liam Gallagher contracted viral laryngitis, amid rumours he and brother Noel had been involved in a bust-up.
But the 'Live Forever' singer's sister-in-law insists they will continue.
"The rumours are absolute rubbish. Even in his sick bed Liam was vowing to get back on stage.
"We were all hoping to go down to V together but sadly it didn't happen. The guys were so devastated. Liam watched from his sick bed."
Snow Patrol stepped in to headline the event and were one of three acts - including Keane and MGMT - to pay tribute to the absent group by covering their hits and Natalie says the sickly singer was delighted by their efforts.
She added to Britain's Daily Mirror newspaper: "Liam was so happy that Snow Patrol and Keane sang some of their songs. He thought that was brilliant.
"He really wanted to keep the spirit of the festival alive and was so impressed. That's all everyone wanted - a good singalong."
Earlier this week, Liam apologised to fans who were left disappointed by the group's absence from Chelmsford's Hylands Park.
He wrote on his Twitter page: "The voice may have disappeared but I'm still here. 1st things first V I'm gutted your gutted, I'm sorry, what can I say, f**k all at the moment.
"Secondly, respect to those bands who covered Oasis last night, even though I might of given some of you s**t in the past.(sic)."