In accordance with Art. 87 EPC a European patent application is only entitled to priority in respect of "the same invention" as was disclosed in the previous application. See also Art. 88(2) to (4) EPC.
Source: http://www.epo.org/law-practice/legal-texts/html/caselaw/2019/e/clr_ii_d_3.htm
Date retrieved: 17 May 2021