The Stayin' Alive hitmaker died in 2012 after a battle with cancer, meaning he never got the chance to meet his grandson Maxwell-Robin, who was born in July last year (13).
Now Dwina has opened her heart to reveal the tot is a shining light in her life and has helped pick her up after Robin's death.
She tells Britain's Daily Mail newspaper, "The baby has brought joy, because we were in a very dark space after Robin left. There was a void. Then there was suddenly something to look forward to - the birth of Maxwell 14 months after Robin had died. Until then it was very lonely. It didn't matter how many people were here. When everyone else was asleep, if he wasn't composing, Robin and I would talk for hours. I miss that.
"When you're in the middle of grief, suddenly you have to pull yourself together because there's a new life there. So you want to make them smile and laugh and give them a happy childhood.
"I do wish Robin had known there was a baby on the way before he died. He loved children and would have been thrilled to know that one was going to arrive in this household."