Harding died earlier this month at the age of 39 after battling terminal breast cancer for more than a year, leaving her former bandmates devastated.
According to The Sun, the girls were already plotting a reunion to mark their 20th anniversary in 2022 with Harding on board, but now that she has died they will reimagine the gig as a tribute to her legacy.
"It's bittersweet, of course. They've all been through the most devastating news and it's beyond tragic," a source told the newspaper.
"But when the time is right they'd love to see a concert in Sarah's memory.
"It would be hugely emotional for everyone involved, but it feels like a wonderful thing to do after everyone had hoped they might be able to do it together.
"They loved her energy and her zest for everything, so it would have to be done in that spirit. And if it could raise some money for charity too, then even better."
Earlier this year Harding revealed that she had planned her own funeral, outlining a plan to have the epitaph 'FFS' on her gravestone. body check tags ::