2.11 Who may represent an applicant before the EPO as receiving Office?
2.11.2.Two or more applicants – common agent and common representative
2.11.006If there are two or more applicants, a professional representative (see point 2.11.003) may be appointed as "common agent" (see point 1.9.003).
2.11.007Moreover, if two or more applicants file the application, they may also appoint one of them as "common representative" (see point 1.9.003). If no common agent or common representative is appointed, the applicant first named in the PCT request form who is entitled to file an application with the EPO as receiving Office is considered to be the common representative ("deemed common representative") (see point 1.9.004).
WIPO PCT Guide, 11.005-11.006
2.11.008If no common agent is appointed, any correspondence is sent to the (deemed) common representative or, if the latter has appointed an agent, to the agent of the (deemed) common representative unless a different address is provided as address for correspondence.