Lightning doesn't strike thrice for Adam Sandler and Drew Barrymore in Blended.

In 1998, the two stars fell in love to a soundtrack of Nena, Culture Club and The Thompson Twins in The Wedding Singer.

Six years later, they turned on the charm in 50 First Dates.

Now, Sandler and Barrymore try in vain to kindle the same irresistible spark in Frank Coraci's romantic comedy of mismatched single parents.

Ivan Menchell and Clare Sera's script has a few nice moments of laughter and heart-warming sentiment including some surprisingly moving discussions between a father and his children about grief and remembrance.

Unfortunately, tenderness is offset by exaggerated physical comedy and cloying sentiment, which shamelessly manipulates our emotions to ensure every parent has tears glistening in their eyes as the end credits roll.

The two screenwriters struggle to interweave a surfeit of gooey subplots around the central romance and consequently only have enough screen time to embellish supporting characters with a single discernible trait: the daughter who hides her femininity behind a pudding bowl haircut; the son nurturing an unhealthy obsession with his babysitter; the genial resort host who continually mispronounces a Greek surname.

The majority of these gags barely walk, let alone run.

Lauren Reynolds (Drew Barrymore) is a single mother with two sons, 13-year-old Brendan (Braxton Beckham) and nine-year-old Tyler (Kyle Red Silverstein), who have been let down badly by her unreliable ex-husband (Joel McHale).

Single father Jim Friedman (Adam Sandler) lost his wife to cancer and is now primary care-giver to three daughters, 15-year-old Hilary (Bella Thorne), 12-year-old Espn (Emma Fuhrmann) and four-year-old Lou (Alyvia Alyn Lind).

Fate conspires to throw Lauren and Jim together on a disastrous blind date.

The parents vow never to see each other again and take their respective broods on a South African safari adventure.

As luck would have it, they are forced to share the same family-sized suite.

Battle lines are drawn between the dysfunctional Reynolds and Friedman clans but animosity mellows into unexpected attraction as Lauren and Jim realise they could be the missing pieces in each other's haphazard lives.

Blended is a terrible title for a romcom.

Director Coraci, who helmed The Wedding Singer, is powerless to perform the same alchemy 16 years later and musical interludes courtesy of the African resort's singing host (Terry Crews) fall flat.

Sandler and Barrymore catalyse screen chemistry which feels more like sibling affection than simmering passion, and their couple's first kiss looks awkward.

Younger cast are more convincing in underwritten roles especially Bella Thorne, who transforms from tomboy into prom queen after a visit to the resort's spa in a scene reminiscent of the 1999 teen romance She's All That.

Alas, Blended isn't all that, not by a long shot.