According to Stepfamilies Australia, last year up to 20 per cent of all "couple" families with children were stepfamilies, a result of one in three marriages in Australia being a re-marriage, the simple fact that people are living longer, and the freedom to leave that came with the advent of the single parent benefit. Sydney business director Melissa Haggerty, 44, credits a strong marriage - and the odd glass of wine - with her move from singleton to step-mum.

"They knew not to mess with me"

She can't say she wasn't warned. When Melissa Haggerty first met Mark, now her husband, at a pub in October 2001, he told her upfront that he had four children. "I've got a '67 Mustang" the single girl cracked. "Wanna swap?"

He didn't. On their first date the very next night, she was ushered into his house by one of the brood. Mark was out at the shops and when he got home, his wide-eyed date was bailed up in the kitchen surrounded by four teenagers - two of Mark's children and two of their friends - who took their seats and stayed, along with his younger two, for dinner. "Oh, God!" Melissa recalls thinking. "It was a little bit overwhelming, but we had a glass of wine and that made things easier. It was fine."

So fine, in fact, that eight months later she signed up for a role that would send most women screaming back to singledom: she became a stepmum to Alisha, then aged 10, Michael,13, Rachel,15 and Ryan 21. "I didn't overthink it, otherwise it probably would have been too daunting," says Melissa, a straight-talking redhead with an easy, throaty, laugh. "You don't meet many people who say, '[Step parenting] is the greatest thing, you've got to do it!"

It helped that the kids, who have a strong relationship with their biological mother, were on-side. "They could see that their dad was happy," says Melissa, "and I think they'd seen a few crazy girlfriends before me. I was really quite normal! The overriding thing was, 'Dad and Mel are really happy'; they knew that they couldn't break that up - and they didn't want to. They really had that maturity."

For Melissa and Mark, who have had full-time care of three of the children at various times, failure wasn't an option. "It hasn't been perfect," admits Melissa, the business director of a media agency, "but it's more teenagers being teenagers, not necessarily because I'm a stepmum. It was like, 'You're a mean old cow because you're making me do this', not '...because you're not my real mum.'"

After the wedding, two habits kept the family solid: One was, where possible, to have dinner around the table. "Everyone sat down and was civilised to each other, even at times when there was less civility happening beyond the table," says Melissa. The other was a nightly glass of wine the couple shared on the balcony, where the children knew they could come and talk "about anything. Mark had definitely set it up that nothing was off limits."

At the same time, Dad was no soft touch. "Mark and I are a really strong unit," says Melissa. "We support each other 100 per cent in any decision. They knew not to mess with me."

To working mum Melissa, the key to her success is simple: "I haven't tried to be anything I'm not. I didn't try to be their mother. I'm very matter-of-fact and down-to-earth. You know where you stand with me. Sometimes, I get home from work and the girls say, 'What's for dinner?' and I say, 'Where do you think I've been? Playgroup?"

Read more stories of stepmums in this month's marie claire.