I need to merge CiviCRM data from a Drupal 6 site into a Drupal 7 site that has an existing CiviCRM installation. The sites are running under Aegir. In both cases the Drupal and CiviCRM tables are in the same databases. The D6 site is on Civi 5.24.3 with about 45k contacts with lots of organisation memberships + events records. The D7 site is on Civi 5.25.
I understand that I can do the laborious export/import process but am hoping someone has a recipe for a more efficient way.