Apologies @Christoph for missing your earlier message. Just an update that we completed the merge successfully, but it took us about 18 months to complete the process. Lots of lessons learned about duplicated, redundant and ambiguous data and configuration.
Having been acquired by a new parent company it looks like we will be going through the exercise again to merge 2 large instances. The fun never ends 😊
Curious to know how the second phase went.
@Craig Nodwell The merger with the new parent company was a huge task. It took about 9 months for the bulk of the migration of the Jira and Confluence instances. There are some outstanding Jira projects remaining, mainly due to issues migrating the test artefacts for the Zephyr plugin.