*** 1/2 (three and a half stars)
The prolific director Joe Swanberg and his improv-ready cast conjure up an engaging comedy about women probing their identity in "Happy Christmas." Kelly (Melanie Lynskey) and Jeff (played by Swanberg), married with a two-year-old (Swanberg's scene-stealing son Jude), welcome Jeff's screw-up sister Jenny (Anna Kendrick) to their Chicago home for Christmas. Jenny's a mess, prone to binge-drinking and just over a break-up, but she's also a creative spark that Kelly, a novelist stuck in her stay-at-home mom status, needs to get going. The byplay between Lynskey and Kendrick, with a boost from Lena Dunham as Jenny's best friend, opens up funny and emotionally authentic conversations about the perils of women "having it all."