It took part-time events organiser Frederick Puah two years to convince his three children to join him in his life-long dream of running a restaurant.

His second child, Vanessa Puah, 27, says that apart from wondering whether they should leave their careers, they also wanted a more even keel in the family business relationship.

"He was more dad than partner," recalls Ms Puah, who is married with no children. "For example, he might say, 'This is what I have in mind, you come and help me.'"

But over the years, her father became more consultative and less authoritative.

Five months ago, the family started British Hainan, a Western eatery in Joo Chiat that also houses Mr Puah's vintage collectibles for sale. Oldest child and former human resource administrator Amelia, 30, cooks. Vanessa, a former graphic designer, and son Clinton, 23, who has just completed national service, are the service crew.

Mr Puah's wife Jessie, 57, is in charge of finance.

Amelia admits she has "flared up at all of them" when, for instance, an order was not communicated correctly to her. She says: "You tend to be more impatient towards family members than with co-workers, so you're not so much on your guard and expect them to take it."

Her parents say they do not expect to hear "please, mum" or "thank you, dad", given the pressure of serving customers. Mr Puah, 57, says: "Living together and working together are two different stories."

Indeed, family counsellors say issues in boss-worker relations can become magnified among family members because of blood ties, as well as family dynamics and histories. Marital and family therapist Benny Bong, 56, says the "main difficulty revolves around boundaries".

He adds: "How do I not let my family quarrels affect my work when I am relating to the same person? For example, how do I know that when my wife objects to a business plan, she is not doing so to spite me over a disagreement we had at home?"

Associate Professor Annie Koh, academic director of the Singapore Management University's Business Families Institute, says: "The uniqueness and the strong inter-relationship between the family and business could potentially result in conflict."

Her advice is for families to define roles at the workplace and play to one another's strengths.

At Orchid Laundry, business development director Harry Toh, 34, says that job roles are assigned according to "personality traits". He and eldest sister Nelly, 49, are the "outspoken" ones, so they look after marketing matters. As managing director, Nelly also oversees washing and delivery schedules.

Their "more patient" second sister, Adeline, 47, is human resource manager. Younger brother Derrick, 41, who is "good with machines" is engineering manager. A fifth sibling lives abroad.

Their 70-year-old father Toh Kun Hai, who started the business 40 years ago, is still the "big boss", who can tick off any of his children if, for instance, he finds soiled laundry on the floor instead of in trolleys.

About five years ago, when Harry, a former programme manager at Hewlett-Packard, first joined the family business, he wanted to automate and expand it. But he was mindful of hierarchy and seniority, that his sisters had been in the family business for 20 years before him. So he says he took "six months to a year to understand the business" before setting out automation plans.

Finally, he laid out the plans at a three-hour family meeting in the office, fielding questions from quality control of pleats to maintenance.

His siblings had already wanted to expand, but were not sure how to go about it. Following Harry's proposals, Orchid Laundry, which was established in 1973, went from two plants and seven outlets to three plants and five outlets. The family cut non-performing outlets.

The Tohs opted to pay everyone the same amount and provide the same benefits, a transparent system which their father decided on from the time Harry's elder sisters came onboard. According to Harry, it is a policy all of them are happy with. He says: "You cannot have one pillar thinner or thicker than the other. All pillars need to be of the same dimensions for the building to be strong."

He declines to reveal their pay but says the "overall entitlement" is better than his previous pay at Hewlett-Packard, where he had worked for five years before joining the family because sister Nelly asked him to "make our business better".

Diamond businessman Steven Lam, 38, says he has had to "manage the strong personalities" of both his wife, Ms Lum May Yee, 40, and his mother Judy.

Fortunately for him, he adds with a laugh, "they both handle different areas of the business, so there's no room to disagree, and I'm not caught in the middle".

Mrs Lam, 65, who started The Canary Diamond Company in 2000 with her husband William, 66, who is managing director and designer, is executive director of operations.

Steven, a former investment banker and luxury brand manager, joined the business in 2009 as business development manager and is now director.

Ms Lum, a former model and actress, joined the following year to do public relations and marketing.

Despite the division of responsibilities at work, Steven had to sort out a sticky problem. Mum wanted him, his wife and their two-year-old son, Aiden, to live near her, so she could be close to her grandson. However, Ms Lum wanted some space, saying they already see his parents at work.

"It took a lot of coaxing for my wife to agree. I told myself to spend time with my own family. So I didn't end up having dinner with my parents every night, and there was a break from work as well," says Steven, who lives in the same private apartment block in Bukit Timah as his parents.

He also had to adjust to younger brother Johnny's entry into the family business. Johnny, 32, joined the business last year after 10 years in the diamond trade in China. Steven says: "I've been kicking his a** as a kid, I forget that he's a colleague now."

But Johnny, who still addresses Steven as "kor kor" (Cantonese for big brother) at work, stood his ground.

Steven recalls: "We sat down to a gentleman's chat. He told me, 'I want to bring my own ideas to the table. Don't see me as your little brother and quash my ideas before you listen to them.'"

The siblings say their contrasting temperaments - the elder brother is more aggressive and the younger more passive - act as checks and balances in decision- making. Working together has brought them new respect for each other.

Says Johnny: "We're a lot closer because of interactions at work. And I respect him not just as an older brother, but also as a professional who makes good decisions."

Steven notes his younger brother's 10 years of all-round experience in China, from inspecting raw diamonds to dealing with clients there.

He says: "I see him as a professional and an equal, no longer as just my little brother."

Although most families working together say they do not talk shop outside the office, the Primalani clan that runs Parisilk Electronics & Computers is an exception. Business is "in our blood", says Mr Mahesh Primalani, 35, head of corporate sales and business development.

He adds: "For us, business and family are very much intertwined. We have lively and exciting discussions, whether it is in the workplace or at the dinner table at home."

Mr Primalani's grandfather started Parisilk as a textiles store in 1952 but switched to selling electronics in 1974. It now has five outlets and employs 10 members of the extended family.

Emotions do "come into play and things can get testy", says Mr Primalani.

For example, the "older generation" measures productivity by the number of hours spent at work. He and his cousins would like better work-life balance.

He says: "We are still working on convincing one another. But no one holds grudges. Once a decision is made, we move on. Ultimately, it's about making money together."