Pete (Mark Wahlberg) and Ellie (Rose Byrne) are a happily married couple who fumble their way into foster care adoption. They take on three siblings, including a rebellious 15-year-old girl, played by Isabela Moner (Wahlberg's Transformers co-star), with predictably tumultuous and mostly amusing results.

Director and co-writer Sean Anders was inspired to make Instant Family by his own experiences with adoption which, happily, makes for a more endearing family comedy than, say, Sean Anders' Daddy's Home 2. Poised indelicately between shameless schmaltz and slappy slapstick, Instant Family may be blunt and messy, but it's easily a career best for the filmmaker behind Sex Drive and Horrible Bosses 2.

Wahlberg and Byrne make for agreeable comic to-and-fro – he's doing his shouty thing, she's doing frazzled – while Moner does most of the melodramatic heavy lifting as a rebellious teen with rowdy friends and unsuitable taste in boyfriends. The script, co-written by John Morris, is aware enough to have Wahlberg deliver a quip about James Cameron's Avatar and the White Saviour Complex, and yet there are some loose ends and jagged edges around the appealing, if treacly central concept.

Moments of what can only be described as ultraviolence sit uneasily between scenes of suburban family bonding. Veteran actors Margo Martindale and Julie Hagerty aren’t given nearly enough to do, to say nothing of a criminally wasteful cameo appearance from Joan Cusack.

There’s a nice-looking dog who serves no narrative purpose whatsoever. Shouldn’t the fluffy Bernese Mountain dog get in the group hug action?

Against that, there’s effective Hallmark sentiment, some terrific darkly humorous banter from Octavia Spencer and Tig Notaro’s case workers, and a grand lump-in-the-throat finale that salutes foster carers.