@Charly-51284 

Hi,
Adding the two new cameras to your account or creating a new account for them depends on your usage scenario. 
    1) If you want to manage the two new cameras with your account, you can add them to your account. If your parents want to manage the cameras, you can share your account with them, or you can share the camera with your parents' account, but their account has limited permissions to the camera.
How to share my Tapo Smart Devices with family?
 

    2) If you just need to watch the new cameras and your parents need to manage/control them, you can create a new account for your parents, then set up the cameras and bind them to the new account, and then let your parents log in to the Tapo app with the new account to manage the cameras. If you want to watch the cameras with your account, you can share the two cameras with your account.

Best Regards