Complex sentence: He may have succeeded his brother directly, as indicated by much later historical sources, or as advocated by Miroslav Verner, Shepseskare reigned between the two, albeit only for a few weeks or months at the most.
Split into simpler sentences: He may have succeeded his brother directly, as indicated by much later historical sources. Alternatively, Shepseskare reigned between the two as advocated by Miroslav Verner, albeit only for a few weeks or months at the most.