Complex sentence: However, the military regime cancelled this election and suppressed all the political parties, including UDN, whose members joined the National Renewal Alliance Party ("Aliança Renovadora Nacional-Arena"), a new party created to endorse the military regime.
Split into simpler sentences: However, the military regime cancelled this election and suppressed all the political parties, including UDN. Most of its members subsequently joined the National Renewal Alliance Party ("Aliança Renovadora Nacional-Arena"), a new party created to endorse the military regime.