Historian Splitter - Backfill

I have a plant site that has been recording history for 5+ years. We recently set up a history splitter to continue historizing to their existing connector as primary, and then to a centralized server as secondary (coupled with a remote tag historian connection). We then use the centralized server for non-shopfloor analysis.

Is there a way to properly port the existing history from the primary database into our centralized server?

The schema is documented, but you are basically on your own. See this related discussion: