The former banker was overcome with emotion as she realised how far the 14-year-old had come since the family began fostering her nearly four years ago.
Elaine, 41, and her husband Jonathan, from East Ayrshire, were organising their 25-year-old daughter's wedding with the help of the teenager.
Elaine said: "She was sitting and listening in and then turned round to me and said: 'Will Jonathan walk me up the aisle?'
"My heart almost stopped. For us it was a momentous moment.
"I always dreamt when I was young about getting married and what it would be like for my dad to walk me down the aisle.
"But these children have all these things stripped from them. They lose their families, their friends, they forget about all the dreams that make them alive.
"And you have to put them back in. I said: 'Of course, he'd be honoured.' It's like a relief came over her - now she can dream about that."
The mum-of-two, who has been fostering for five years since leaving her corporate job, spoke out yesterday at a conference held for the 68 new foster parents in Glasgow.
In the past year, Glasgow City Council's Families for Children Service has recruited and approved the carers to help provide support for the city's vulnerable young people.
The new recruits represent the biggest rise in foster carer numbers in one year since the council launched a recruitment campaign in 2005.
The council now has more than 550 foster carers - almost double the amount five years ago, making it the biggest provider of local authority foster care in Scotland.
At the event held at the Emirates Arena, council leader Gordon Matheson announced a 2% rise in the weekly allowances that are paid to foster carers to support children.
Elaine urged foster parents to consider looking after children on a long-term basis.
She began fostering after her dad died, when she realised she had "a lot of parenting" still in her.
She said: "My dad died quite unexpectedly. At the funeral loads of people were saying: 'Your dad took me in when I had a drink problem, your dad changed my life.'
"And it really touched me. I spoke to Jonathan about it and we went to bed that night and the next morning I picked up the phone. We've never looked back."
Her foster daughter was originally on a short-term placement but is now expected to be in their care for the rest of her childhood.
Elaine said: "It's just amazing. It's a privilege because she is such a wonderful girl and has overcome so much.
"It teaches you a lot about yourself being a foster carer. You have skills you didn't even realise you had. You learn a lot from them because you see what they overcome, you see what they can achieve even after their start in life."
Elaine said her foster daughter now knows she has a future with the family.
She said: "That's a massive thing for a foster child to take on board.
"For her to get to the point and not just survive but to actually start to succeed in life is down to all the work she has put in.
"We're honoured actually as foster carers to just be part of that journey."
The council is hoping to recruit more foster carers to look after children long-term.
Mr Matheson said: "Foster carers are a vital part of our care system. When families run into difficulties, it's often foster carers who step in to pick up the pieces.
"More than anything children need a stable, warm and loving environment in which to grow and that's exactly what foster carers provide.
"Like any family, there can be challenges, but as the great majority of carers will testify, fostering can be the most rewarding experiences of their lives."