My Info Index uses Apple’s Core Data database to store all your information. Core Data will replicate the database across multiple devices if each device is signed on with the same iCloud account.
If changes are made on one device, it is important to wait until those changes have been updated to a different device before making changes on the different device.
If the same Objects or Profiles are created, edited or deleted on different devices, before the updates between those devices have occurred, parts of the data may become corrupt or missing. If this is something you think you will do, you should export the data for backup, after making changes, in case you need to recreate something. BACKUPS ARE ALWAYS A GOOD THING.