Over the years, Merryn progressed through various teams, reaching National Youth Finals with Murrayfield Wanderers and Edinburgh Harlequins. 

Notably, she competed with Corstorphine Cougars in the 2023 Sarah Beaney Cup Final at Murrayfield and was a breakthrough star of the Celtic Challenge for Edinburgh Rugby. 

Merryn earned her first call up to Scotland Women in the 2024 Guinness Six Nations. Although she was not capped, she went on to earn selection for the U20 side in the Six Nations Summer Series later that year. 

In 2024, Merryn was named the Scottish Rugby National Player of the Year at the Community Recognition Awards. 

Upon selection for the U20 side in 2025, Merryn was selected as part of the team leadership group and was appointed captain for Scotland in their opening match against England.

Merryn has completed a Level Six Development Player Programme for rugby at Borders College and is currently supported through the East Regional Training Centre with Scottish Rugby.