In R 18/09 the Enlarged Board held that the principles set out in G 3/99 (OJ 2002, 347), also applied to petition for review proceedings, namely that a plurality of persons acting in common must be treated as a single party (a "group party") and that such a group party must act through a common representative.
Source: http://www.epo.org/law-practice/legal-texts/html/caselaw/2019/e/clr_v_b_3_10_3.htm
Date retrieved: 17 May 2021