I use two timelines for my story. A timeline for the events of my story. And a second for events that predate my story: family histories and recent events in Iraq (since one of character's was involved). I only bother to sync the story events timeline. It sounds like all five of your timelines try to do the same thing. It'll probably be a real pain to get them all merged, so considering tossing out those with the least useful data. Hopefully you'll only have two (or if lucky only one) you need to mess with. Start with the most complete timeline and sync that to Scrivener with the timeline as boss. Then close the timeline and open the second timeline and start your sync with the same Scrivener file. Decide on an item-by-item basis if the Scrivener version rules, or the timeline version. Anyway, eventually you'll get down to one timeline and discard the rest. It's going to take some time. Best of luck!
You can copy and paste events from one timeline to another.