I think that if there is a oneshot that of course was a stand alone story, and then is later turned into a series there should be two separate entries for them. For example: Nisekoi and Half & Half (SEO Kouji). The series usually starts with the same premise as the oneshot, and of course is only a series because of the popularity of the oneshot but I feel that they should be listed separtely. It would also make it easier on the lists, since I had the oneshot in my complete list and suddenly found out it was a series entry now and I changed it to my reading list (I mean who thinks a oneshot will turn into a manga series three years later anyway?).