As she proved with 2009’s “Humpday,” director Lynn Shelton is a talented filmmaker not afraid to include LGBT themes in her work. Her latest is “Your Sister’s Sister,” which has a prominent lesbian theme, and — like “Humpday” — is worth seeing even if the gay angle is a bit problematic.

As the film opens, Jack (Mark Duplass) is mourning the death of his brother Tom, a year later. After a friend waxes eloquently about Tom at a gathering, Jack stands and speaks the warts-and-all truth about the deceased and it’s clear Jack is still a wreck. His best friend is Iris (Emily Blunt), who was Tom’s lover. Seeing Jack is an emotional mess, she suggests he go to her family cabin on an island in the Pacific Northwest that is supposedly empty. “It has no internet, no TV… maybe a few forks,” she promises.

When he arrives he discovers he is not alone after all. Iris’ half-sister, Hannah (Rosemarie DeWitt), is there. She is a lesbian who has just broken up with her girlfriend after seven years. She is also a vegan whose food choices (such as dehydrated banana pieces) provide some of the film’s funnier moments. The two share a drunken late night and reveal some truths.

After a world premiere last fall at Atlanta’s Out on Film Festival, “Legalize Gay” returns for Stonewall Month for a screening to benefit three locally based LGBT groups.

The film, which screens June 11 at Midtown Art Cinema, focuses on several diverse individuals, gay and straight, working to advance LGBT equality. Atlanta ties include a profile of Spelman University alumna Jeshawna Wholley, who organized the first Pride event at the historically black college and was later invited to meet President Barack Obama; and the StandUp Foundation, which is based in Atlanta and was created by U.K. rugby star Ben Cohen.

“When we showed the film as a world premiere in October, it was brand spanking new, and since that time has been well received at college campuses and other festivals,” said Jim Farmer, Out on Film festival director.