Complex sentence: The boys had previously performed together in' and the film "Lima Elang"; they had also all performed well in singing competitions, and Effendy had previously established a group of child singers which performed under the name Superkids.
Split into simpler sentences: The boys had previously performed together in' and the film "Lima Elang"; they had also all performed well in singing competitions. Effendy, meanwhile, had previously established a group of child singers which performed under the name Superkids.