Complex sentence: He moved to Denmark in 2011, and the following year he changed his swimming nationality to Danish; and after that he can only set Danish records, not Faroese and he can only represent Denmark in swimming competitions.
Split into simpler sentences: He moved to Denmark in 2011, and the following year he changed his swimming nationality to Danish. After that he can only set Danish records, not Faroese, and he can only represent Denmark in swimming competitions.