Complex sentence: They actively contributed to the preparation of the current Spanish Constitution of 1978 and the Statutory Law on Religious Freedom of 1980, actually in force, constituting the same year the Union of Islamic Communities of Spain, with registration entry in 1991.
Split into simpler sentences: They actively contributed to the preparation of the Spanish Constitution of 1978 and the Statutory Law on Religious Freedom of 1980. In the same year the Union of Islamic Communities of Spain emerged, with registration in 1991.