Sister act at Merrimack
Jill Tanner and Felicity La Fortune in Equally Divided. Photos: Meghan Moore.Ronald Harwood's Equally Divided (at the Merrimack Rep through this weekend only) often feels like a theatrical time machine: step into it, and you're transported back to the days of Terence Rattigan and Tea and Sympathy, and a whole twilit world of melodrama populated by lonely women and ambiguously gay men, where much hangs on gentee…