Problem Definition

When two large instances of Confluence need to be merged the process of exporting and importing spaces individually becomes very cumbersome

Suggested Solution

It would be useful to have support for support importing multiple Confluence Server spaces.
A tool similar to the Cloud Migration Assistance for Confluence could work

Workaround

1. Export spaces by either:
   1. Individually Export the desired space as a full XML backup
   2. Or per this community post, utilize Bob Swift's Confluence Command Line Interface (CLI)'s and its exportSpace action to bulk export spaces to XML
2. Restore each of the spaces to target Confluence instance

• You can't import into an earlier version of Confluence. So if the Confluence instances are on different versions, you may be limited by this and need to upgrade
  • For example, if you export a space from Confluence 5.9, you can't import it into Confluence 5.5.
• If the space to be imported is very large, you may need to temporarily increase the memory available to Confluence. See How to fix out of memory errors by increasing available memory