Hi Szar78, thank you for posting in Apple Support Communities.
There are two options I can suggest as follows:
Share iCloud calendars on iPad
In the Calendar app, you can share an iCloud calendar with other iCloud users. When you share a calendar, others can see it, and you can let them add or change events. You can also share a read-only version that anyone can view but not change. The following link explains this in more detail:
https://support.apple.com/en-au/guide/ipad/ipadc2a14a22/ipados
Add iCloud calendars on iPad
- Go to Settings > Mail
- Add iCloud account (May require code from AppleID re two-factor authentication e.g. your wife's device(s))
- When added, select iCloud account
- Turn off iCloud Mail and Contacts
Hope one of the options helps.