The owner of the original email address can set up the profile and share it with the Organisation. Then, in the profile, there is a ‘share’ button. Click on that and it will open with a dropdown menu – enter the name, email, relationship, and make sure the Access type is set to ‘View and Modify”. Save it, and then both parents have the necessary access to view and modify (which includes ability to respond to eforms).
You can find step-by-step instructions here: https://support.operoo.com/portal/en/kb/articles/how-does-a-user-share-a-profile-with-a-second-parent-or-carer
This is very useful feature for families with shared care arrangements, or who require both parents to have access to the Operoo profile.