Each found the answer to that question in the other - in August last year they merged their agencies to form GSL Promotus, now one of the country's largest independent ad agencies.
Clearly Graham and Grice fiercely value their independence but they also reckon it's a valuable commodity to others.
"We both got approached by the big globals twice and took it right through to due diligence," Grice says.
"But, for me, the biggest payback of having my own business has always been being in control of my own destiny and I didn't want to give that away," she says.
"Both Leigh and I had good businesses of a reasonable size and so we thought by joining them together we'd create a viable alternative - of a decent size with a strong service offering - for clients who don't want to be with the big multi-nationals."
GSL Network had a track record of successful digital and social marketing campaigns, particularly for government clients, while Promotus had formed some longstanding relationships with commercial customers - cornerstone client Suzuki, for example, has been with Promotus for 18 years.
Grice says bringing together businesses with complementary strengths and no client conflicts helped smooth the merger path. But combining two offices and cultures still took time, along with a lot of support from professional advisers like lawyers, bankers and accountants.
The main challenge the company now faces is external, Grice says.
"The main thing for us is keeping at the forefront of the changing world we live in," she says.
"The media landscape is changing all the time. It's fragmenting and the way consumers consume media is constantly changing. It's a very dynamic environment, so we have to keep pushing ourselves to learn, innovate and explore, and to challenge each other and be open to new ways of doing things all the time."
The primary source of that fresh thinking comes from within the company, Grice says.
Creating a culture where people can share ideas, collaborate and learn from each other is the foundation that underpins the whole operation.
The wider industry - which Grice says recognises and values the firm's independent stance - has also been an important source of support.
More broadly, though, Grice says she'd like to see greater recognition for business owners who have sunk significant proportions of their wealth into companies and who continue to invest in growth.
"I think there could be more support for SMEs to grow and prosper.
We provide jobs and any profit we make stays in New Zealand - which I think is a big story and one that should be recognised with some tax incentives because, perhaps as we reached certain levels of size or scale, it would encourage us to keep growing."
With the merger now bedded in, part of the longer-term growth plan is for the firm's majority owners - Graham, Grice and general manager Jodi Macauley - to sell down their shareholdings to key employees over time.
It's a plan they figure will secure the company's independence well into the future and recognise the fundamental role staff play in its success.
"I've got a business mantra I've always used and that's, 'Look after the relationships and the revenue takes care of itself'," Grice says.
"As an agency we've got a lot of staff and clients who have been with us quite long-term and I think that's one of the biggest measures of our success - especially in this industry because it's so full of change."
