Tina Howe's new stage work is a family reunion play set on Boston's historic Beacon Hill. On the eve of her first New York one-woman show, artist Mags Church (Frances Conroy) returns home to help her aging parents pack up for their impending move to Cotuit on Cape Cod. Mags's condition for her visit is that she at long last be allowed to do a portrait of Fanny and Gardner Church (Marian Seldes and Donald Moffat). Hence the title, ''Painting Churches.''
As properly proper Bostonians, the senior Churches exhibit the mingled eccentricities, quirks, and propriety of their Brahmin tradition. Gardner, a poet and scholar of distinguished achievement, is supposedly writing a magnum opus - meanwhile teaching his parakeet to recite Gray's ''Elegy.'' Fanny runs the diminished household and haunts the neighborhood thrift shops for bargain designer hats and other haute couture. Gardner responds to the artist in Mags. Fanny does not and never has. Getting her parents to take their portraiture seriously challenges all of Mags's tact and ingenuity.
The surface fencing leads to the complex of revelations that provide the core and conflict of ''Painting Churches.'' Mags recalls a traumatic childhood disciplinary ordeal and, later, the way in which her debut at a New York art exhibition was overshadowed by Fanny's outlandish behavior. Fanny shocks her daughter by acquainting Mags with the extent of Gardner's mental deterioration. The Churches are finally painted, but not without pain to all concerned. With each scene, the Beacon Hill house grows emptier.
Although strongly cast and handsomely produced by the Second Stage at the South Street Theater, ''Painting Churches'' still resembles somewhat a work in progress, as yet not fully certain of its focus or direction. The comic small talk - with its indirections and evasions - tends to pall. The strength of her richly allusive play lies in the sensitivity of Miss Howe's observation.
While Mags appears to be the author's central object of concern, it is Fanny - aided and abetted by the handsome Miss Seldes's floridly amusing performance - who dominates much of the action. Notwithstanding finely tempered performances by Mr. Moffat and Miss Conroy, Gardner and Mags remain the subordinate figures in this Boston family portrait.
The production staged by Carole Rothman has been beautifully and observantly designed by Heidi Landesman (scenery), Frances Aronson (lighting), and Nan Cibula (costumes, including a succession of hats with character).