Hello hambuer,
Welcome to Apple Support Communities.
We understand that you want to add your wife, so that she also has access to HomeKit and not replace yourself. We are happy to help.
Please try the steps here to invite someone and to allow remote access and edit permissions for users here: Share control of your home - Apple Support
Invite someone to control your home
- Open the Home app on your iPhone, iPad, or Mac.
- Tap or click the More button
, then select Home Settings. If you have multiple homes set up, choose the Home that you want to invite someone to, then select Home Settings. - Tap or click Invite People.
- Enter the person's Apple ID that they use with iCloud.
- Tap or click Send Invite.
Allow remote access and edit permissions for users
If you set up a home hub, you can manage remote access and edit permissions for people that you invite to control your home. If you don't have a home hub set up, they can only control your accessories while they're at your home, connected to your home Wi-Fi network, and within range of your accessories.
To manage remote access and change permissions for a user, open the Home app and follow these steps.
- Tap or click the More button
, then select Home Settings. If you have multiple homes, choose a home, then select Home Settings. - Under People, select the person that you want to edit permissions for, then choose the following:
- Control Accessories Remotely: Turn on to allow users to control your accessories from any location. Turn off to allow users to only control your accessories while they're at your home.
- Add and Edit Accessories: Turn on to allow users to add and remove accessories, scenes, automations, and other users.
- Tap or click Back, then Done.
Shared users can't add HomePod, Apple TV, or any AirPlay 2-compatible smart TVs or speakers to the Home app. You can only add these devices if you're the owner of the home in the Home app.
Let us know if you have further questions.
Take care.