“Good Posture” is said to have begun with a dare when Dolly Wells was pushed by Jamie Adams, her director on “Black Mountain Poets,” to make her feature directorial debut (similar requests were issued to Jessica Hynes and Tom Cullen, who responded with “The Fight” and “Pink Wall,” respectively) and while she was initially resistant, she had been watching co-stars Grace Van Patten and Norbert Leo Butz night after night in Hamish Linklater’s off-Broadway “The Whirligig” and was inspired to put pen to paper. Naturally, both appear in “Good Posture,” but it is the idea of the challenge itself that have had the most influence, telling a most endearing coming-of-age story across two generations under one roof for a pair of women who need to be shaken from their comfortable routines to find a greater sense of fulfillment.

When we meet Lillian (Van Patten), it may feel as you’ve already been introduced as the slovenly former film student is ending a two-year relationship with her boyfriend Nate with few prospects to look ahead to, romantic or otherwise. Aimless but financially secure thanks to her father Neil (Butz), who sees his cash as a way to be present in her life while he’s off in France with a new girlfriend, she can be seen immediately wandering around Brooklyn, but only as far as the end of the block where Neil has arranged for her to stay with Julia Price (Emily Mortimer), an old friend of her late mother’s, and her husband Don (Ebon Moss-Bachrach). It becomes clear that Lillian could’ve used some parent in her life for guidance, but she isn’t going to find it with the Prices, with Don about to hit the road as a touring musician and Julia retreating to her bedroom as a J.D. Salinger-level recluse who left the public eye after her debut novel and barely sees anyone inside her house. When left alone with Lillian, save for the occasional visit from her dogwalker George (Timm Sharp), Julia begins to express her displeasure with the arrangement through beautifully penned notes left on her pillow, gently nudging her towards the door.

Lillian doesn’t leave, taking Julia’s admonition to “be brave” not as inspiration to flee the nest, but burrow further inside of it by making a documentary about the author and as she films interviews with admiring peers such as Zadie Smith and Jonathan Ames without Julia’s knowledge, the anticipation builds towards the inevitable eruption of anger to be expected from the private writer when learning of the unauthorized bio. Actually having Smith and Ames on hand, among other literary heavyweights, gives “Good Posture” considerable legitimacy, but then again Wells achieves that all on her own with the bittersweet comedy so precisely capturing this elusive feeling of frustration for both women with seemingly no cure. (Adelina Bichis’ wonderfully slippery editing and Ryan Eddleston’s airy camerawork contributes to portraying such a messy moment with Grace.)

Naturally, Wells brings to bear the dry wit she’s long been known for in her performances and is generous in terms of parsing out some murderous one-liners to all her actors, though she seems to afford special consideration for John Early, unlocking his full comic potential as Lillian’s blissfully brash and blase camera assistant Sol. Van Patten, such a winning presence in films such as “Tramps” and “The Meyerowitz Stories,” is once again a force to be reckoned with here and in playing someone seemingly unaware that they have that in them, handles the subtle emotional shifts of becoming emboldened quite delicately. To know that a most talented first-time director might’ve been experiencing the same thing behind the camera as her lead makes it all the more moving.

“Good Posture” does not yet have U.S. distribution.