Complex sentence: MEDAC became moderately popular, was approved by Etienne Ngounio (the Dacko-appointed president of MESAN), and received significant support in by-elections on 20 September.
Split into simpler sentences: MEDAC became moderately popular and was approved by Etienne Ngounio, the Dacko-appointed president of MESAN. The party also received significant support in by-elections on 20 September.