5 Pre-upgrade considerations for existing databases
Make sure that all the AG Service users (login user id) in all the databases that are to be merged into single database are in sync with the DEFAULT ENTERPRISE. If there are AG Service users in other enterprises which do not exist in the DEFAULT ENTERPRISE, then you can either rename their login user IDs to map them to existing AG Service users in the DEFAULT ENTERPRISE or delete them. If extra users are found in other enterprises during multi-tenant database migration, then they will be marked disabled and you will not be enable them later.
Make sure that all the event & indication and who-drug encoding dictionaries used in Console > System Configuration > Common Profile Switches > Case Form Configuration > Auto Encoding, Dictionary and Central Encoding
section and Console > Business Configuration > Studies > Enable Study Specific Encoding > Auto Encoding
dialog, in all databases that are to be merged into single database are already loaded in the target database with the same name. This is required to enable the automatic linking of dictionaries configured in the separate databases to the already existing dictionaries present in the target database during the database merge script/process.