"I remember making a lot of friends and we'd go away for competitions - places far away like Hamilton and Dunedin, we'd all hang out together after the competitions," she says.
Cossill was talked into getting involved again by her old coach, Tiffany Rose, and has become the main coach this year after Rose passed away suddenly. The girls in the team have a rose sewn into their uniform in her memory and as a tribute to her tireless support.
Kilarn has three sets of sisters competing. It's very much a family affair for the Pask sisters, Isobel and Abigail, whose mum, Lisa, is the team manager. Dad Alan has also been called up at the last minute to do the music after one of the men fell ill.
Another set of sisters, Paige and Taylor Bell, love marching, but not so much being on the same team - in most other sports they would be separated into age groups.
"I like the display dance routines best. Everyone claps when we do a flip, but it's a bit embarrassing to get all that attention,"says Paige, who also says she likes to win.
As I'm talking to another group, Counties Kilties, two girls hold hands and dance around. A women sitting nearby says crossly: "Stand at ease, girls, and in line!"
It all seems quite strict. But it's the discipline the parents of the girls competing here today tell me they are most keen on.
Counties Kilties' leader, Amy Clements, has been marching for six years but it's the first time she has led the team with a broken collarbone. A chain fell on her at school, but she looks more than happy to be at the competition rather than at home resting.
The pom, pom, pom of the big band music starts to play through tiny speakers. The competition is about to begin.
The first group performs to a selection of marching music I'm sure is unchanged from my mother's marching days, when she remembers looking up to see her father waving at her over his newspaper. It's all as expected, very formulaic and precise.
The second routine though is what's known as "display", which means the girls can do more freestyle dance routines, with more modern music.
This section is supposed to be a bit like cheerleading, except the moves the team are doing are still cutesy, in line with the girls ages, unlike some of the more risque cheerleading dance steps - marching seems a much more innocent alternative.
A medley of music includes Candyman, a rap song, Britney Spears and finally, Guy Sebastian's Who's That Girl ends the routine. Another group lines up with its leader about to blow the whistle to start their turn in the spotlight.
The girls beam with pride. If you'd like your children to learn discipline, have fun, keep fit and have a good chance at winning - the Kiwi, Fernz and Masters sections only had one team competing in their grades - or you want to join the adult ranks, this may be the sport you've been searching for. But hurry, before it's lost for good.
Step to the beat
More about where you can join up is at Marching Auckland or on their Facebook page, or ph (09) 480 5048 or 021 026 22148. The website has all the contact details for Team and Association members. Email: niecymaria@gmail.com
The next Auckland Championships are on Saturday 3 March, 12.30-3.30pm at Alan Brewster Recreation Centre, Tavern Lane, Papatoetoe.
