media captionWATCH: "Don't call me 'Dad' at work!"

Ross Testa, 24, set up a successful social media advertising agency while still at university. He turned it into a family business by employing his sister and then his father. Ross and his father explain how they make it work for our business advice series, CEO Secrets.

"When I'm doing new business pitches to clients," explains Ross, "I'll say: 'I'll now pass you over to Roy. It's just something I have to do. Back home he's 'Dad', in the office, he's 'Roy'."

"If my staff see him as 'Roy'," he continues, "I've got to respect that and see him as 'Roy' too. I actually have him on my phone as 'Roy' now, as well."

Roy (aka "Dad") listens intently as his son explains their business relationship.

"It's one of the first things we said," adds Roy, when he can get a word in. "I don't want you talking to me on a Zoom call and calling me 'Dad', it's just not professional enough."

Clients pick up on these issues all the time, says Roy. But it can actually work in the father-son team's favour.

image copyright3 Headsimage captionYounger sister Jodie was Ross's first family hire, followed by his father

Ross set up the 3 Heads social media agency in 2018 while still at Nottingham Trent University. It creates digital content for brands and personalities such as sports celebrities James Haskell and David Haye.

The start-up got an early break when Lord Sugar spotted the agency's work and hired Ross to make video content for one of his companies. The start-up became successful enough for Ross to pursue it full-time after leaving university.

The firm now has 10 full-time staff and has worked with clients like Chelsea Football Club, Huawei, Volvo, Maryland Cookies and Silverstone race track.

In 2019, the agency generated sales of over £500,000, more than double its previous year. In 2020 turnover dropped to £350,000 with the impact of the pandemic, but 3 Heads say they are on track to hit £1m in sales this year.

Roy Testa, 54, quit his job to join as managing director in August 2020.

image copyright3 Headsimage captionRoy Testa worked for many years in the world of newspaper advertising

However, Ross's first family hire (and first employee) was one of his sisters, who he poached from carmaker Audi where she worked as a senior service advisor.

"We're a close-knit family and growing up I had a great relationship with my younger sister," explains Ross.

"I'd worked so hard and sacrificed everything for this business, so I needed someone I could trust to introduce to clients. And I just knew Jodie would be the right one."

"I wouldn't do it with my mum or my older sister!" he adds.

It works because the skill-sets match, agrees Roy.

"Ross has got great networking skills, Jodie has got organisation skills and I bring in the experience they don't have – and try and manage the energy."

Roy worked for decades in print advertising for newspapers. This is what first inspired Ross to take an interest in marketing, as his father often discussed his work at home.

Stories about the buzz of meeting clients always intrigued him as a child, remembers Ross.

Roy brings his experience to the firm, but freely admits he knows less about the digital aspects of the business. On these matters, he defers to his children.

image copyright3 Headsimage captionRoss got a big break doing some work for Lord Sugar

He joined his son's company to help it grow, but he says it means more than that to him.

"I'm here because I've mentored and grown a lot of people in their careers, and now I want to do the same for my kids, to see them come through. It's nice to have the opportunity to do something like that for your own, you get so much satisfaction."

However, keeping a distinction between work and rest, colleagues and family, is difficult – both admit this.

Both Ross and Jodie still live at home. They now have an office, which helps, although during lockdown they were very much trapped in the house.

"My mum and older sister, poor them, they didn't get a word in at the dinner table," says Ross.

"It's not nine-to-five, it's nine to midnight," he explains, "you are in work mode all the time."

image copyright3 Headsimage captionThe family team working together at Silverstone race track

The company is Ross's baby, so now that Roy has joined as 'managing director', who is ultimately in charge, father or son? Who is CEO?

This feels like an awkward question. "Our dream was to build something together," says Ross.

Roy nods.

Roy himself worked with his parents for a period of time and he says this is something he feels comfortable doing for the next generation.

"But really, we're not big or formal enough to talk about 'CEOs'," adds Roy, "we don't have big egos."

So, what advice do they have for other people who employ family members?

You need to treat your relations exactly the same as other staff, says Ross.

"For example, if I think I can abuse the fact that I can speak to Jodie a bit differently because she is my sister, your staff will see that."

"Don't kid yourself it's going to be easy," adds Roy. "It's not a joy ride, you have to work twice as hard as a family member just to justify your existence."

But one thing he hadn't realised, he adds, is just how much clients appreciate the human side of working with a family business – with all the small confusions that can entail.

Follow CEO Secrets writer Dougal on Twitter: @dougalshawbbc