John Hopewell Chief International CorrespondentHBO Europe and Berlin-based Dreamer Joint Venture Filmproduction have boarded “Trust Me,” Joanna Ratajczak’s probing doc feature on a real life couple’s experimentation with an open relationship.“Trust Me” will be presented at Locarno’s Match Me networking event by Stanislaw Zaborowski, at Warsaw’s Silver Frame, the project’s lead producer.