Mrs O'Brien said serving was a family affair. As well as her father serving in World War I, both her brothers served in World War II - one captured as a prisoner of war in Crete.
She was in the Women's Auxiliary Air Force for almost five years and described the experience as an eye-opener.
"I went in like a lamb and came out like a lion."
Mrs O'Brien, who was only about 19 when she joined, admitted she was quite innocent and learned a lot during her time.
"Strangely enough it was a very happy time. We were all doing our bit."
While her father rarely spoke about his experience of the war, she said he was "the proudest man" when his two sons went off to war and his two daughters were doing their bit for the war effort.
Mrs O'Brien said people were still generous with their donations, and not many would walk past without giving something.
She said she loved the company and the people she met while selling the poppies.
Amara said it was the first time she had sold poppies with "nana".
Her mum Alicia thought it was a nice idea to get the younger generation involved and create lasting memories for her daughter.
Amara said she knew she was selling poppies because there had been a war "in the olden days" and "lots of people were shooting people".
People wore poppies to remember them, she said.
