Written in an article by The Independent 'Northern Ireland ‘can rejoin EU after Brexit if it votes for reunification'. A statement from the Brexit Secretary on an Ireland reunification says:
“If a majority of the people of Northern Ireland were ever to vote to become part of a united Ireland the UK Government will honour its commitment to enable that to happen.”
“In that event, Northern Ireland would be in a position of becoming part of an existing EU member state, rather than seeking to join the EU as a new independent state.”
Have there been any other occurrences of (re)unification for membership of the European Union or its predecessor other than that of the 1990 unification of East and West Germany to join the EEC, or any serious political discussion within a member state about doing so?