Complex sentence: Sources conflict about An Lushan biological father's origin and surname; for example, as to whether An Lushan's father had the surname Kang or not: he took the name of An from his stepfather An Yanyan.
Split into simpler sentences: Sources conflict about An Lushan biological father's origin and surname. Source are conflicting as to whether An Lushan's father had a surname of Kang or not; he took the name of An from his stepfather An Yanyan.