Moreover, if two or more applicants file the application, they may also appoint one of them as "common representative" (see point 37). 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 38).
If no common agent is appointed, any correspondence is sent to the (deemed) common representative. If the latter has appointed an agent, it is sent to the agent of the (deemed) common representative. A different address may be provided as address for correspondence only if certain requirements are met (see point 109).
Source: http://www.epo.org/applying/international/guide-for-applicants/html/e/ga_b_20.html
Date retrieved: 30 December 2018