AOL email addresses syncing between iPad Pro 12.9 and iPad Pro 10.5.

Outside of Educational and some Enterprise environments, iPad (and iPhone) are essentially single-user devices that are not intended to be shared.

If all your devices are sharing a common AppleID as stated, you’ll encounter all kinds of issues with unintentional and/or unwanted sharing of sensitive/private information. You’ll not be able to reliably maintain any kind of data separation.

The Golden Rule: Don’t share an AppleID between users. Each user should have their own AppleID for their own exclusive use - linked to their own primary email (and secondary/recovery email addresses and trusted telephone numbers). 

You would be best advised to separate your digital identities and configure a new AppleID for your wife.

After separating your identities, you can continue to selectively share purchased Apple Services, Subscriptions, Apps and Media using Apple’s Family Sharing features:

Family Sharing - Apple

Set up Family Sharing – Apple Support

Share App Store, iTunes Store and Apple Books purchases with Family Sharing – Apple Support

How to create a new Apple ID – Apple Support

https://www.imore.com/how-set-up-family-sharing-iphone-ipad

First, be aware that Apps are permanently associated with the AppleID that was used to purchase them. As such, as Apps were presumably purchased using your [previously shared] AppleID account, the Apps will be associated with you own AppleID. As such, you may wish to share purchased Apps using the Family Sharing feature - from which you can selectively share purchased Apps, subscriptions and Apple services.

Family Sharing - Apple

Set up Family Sharing – Apple Support

Share App Store, iTunes Store and Apple Books purchases with Family Sharing – Apple Support

How to create a new Apple ID – Apple Support

https://www.imore.com/how-set-up-family-sharing-iphone-ipad

As you have previously shared a single AppleID, with the exception of email accounts, separation of your respective data on the iPad will be almost impossible. Ideally you will completely erase the iPad that you are transferring to your wife - as this will completely wipe the iPad and remove the Activation Lock that will otherwise cause issues. To do so, you would follow this process:

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

If you are unwilling to fully erase the iPad - after which you would cleanly setup the iPad again “as new” - you must first remove the existing Activation Lock. From iPad settings:

Settings > [Your Name / AppleID > Find My > Find My iPad - set to OFF

Having disabled the Activation Lock, you can now sign-out from iCloud and your own AppleID:

Settings > [Your Name / AppleID] > Sign Out

During the sign-out process, you will have opportunity to keep a local copy of data stored in iCloud. You must carefully consider the implications of this choice…

• If you keep a local copy of your iCloud data, sensitive data will be copied to the iPad - including all your saved account Passwords (i.e., your Keychain), Photos, Notes, Messages, Contacts, Calendars, Reminders and iCloud Files. When signing-in with a new AppleID, all this data will be merged with the new AppleID account. There is no easy method by which to undo this merge - other than painstakingly removing corresponding data.

• If you don’t keep a local copy of your data, only existing local files will be retained; all iCloud data will be purged from the iPad.

Once signed-out from iCloud, a restart of the iPad is recommended. After restart, your wife can sign-in with her own AppleID.