For most people using iOS and macOS, the best place to store your travel plans is on iCloud Drive. You can then create them with one device and view or update them with another. You could create your travel plans on an iPad or Mac. Whilst your travelling, you can then use your iPhone to view the plans, get directions, and add items such as your expenses.
If a folder hasn't been created for TravelPlanr, create a folder to store your travel plans. You could also create sub folders for different countries or years.
The travel plan is stored as a file on your computer. You can copy, move, rename or delete the file using Finder on macOS and the Files app in an iPhone or iPad.
The travel plan file must have a filename extension of "tplan". This will be added automatically by macOS in most cases.
You can create a backup of your travel plans using Finder or the Files app. You might want to name your backups with a version number or date in the file name. You can open your travel plan, and compare it with any older version. Any changes can be selectively copied into your current version.
You can send the files to your friends to view or update if they also have TravelPlanr installed. Your friends may update the plan and return it to you. You can then compare their plan with yours and selectively include their changes in your version.