Jason Stinsmuehlen, formerly of TBWA/Chiat/Day/Los Angeles, has joined Mullen in Wenham, Mass., as group creative director. He will partner with group CD Jim Hagar to oversee creative for General Motors, Nextel, Progess Energy and other accounts. ... Canadian director Trevor Cornish has signed with Twist Films in Minneapolis for U.S. representation. ... Composer Paul Bessenbacher has joined the staff at Admusic in Santa Monica.