I have one app, now I want the bundle – can I “upgrade?”

Yes! Apple allows you to pay the difference between the bundle price and whatever you paid for the one app in the bundle that you already own. To do so, navigate to the app bundle page from the app store app on your iPad by either searching for “In person sales bundle” or by clicking here from your iPad: https://itunes.apple.com/us/app-bundle/id922521498?mt=8&uo=4&at=10lb6Z&ct=ssweb

Choose “Complete my bundle.”