How many appointments are there, and are they in an iCloud calendar already? In iOS itself, there isn't a way to edit multiple events at the same time.
If these events are in a calendar that is going to iCloud, you can just go to icloud.com, it's a lot faster to edit the events using a mouse.
And preferably, if you have a mac with your icloud account set up on it, you can actually hold down SHIFT and select all of these events and then right click and change them all to your desired calendar with a single click.
If they aren't on an icloud calendar, you're gonna have to change them one by one on the device itself. You can do this by tapping on the event itself, tapping "edit" for the event, and tap on "calendar" and change it to the calendar that you're sharing with your wife.
Best of luck!