If a Register is not shared during it's creation, you can share the register directly from its interface by selecting the appropriate sharing options and specifying the recipients.
Go to the registers section and view all available registers.
Select the register you wish to share, click on the three dots, and then choose "Share."
Enter the email address(es) of the user(s) you want to share the register with and define their access level (Admin access, Can view only, or Can edit).
Click "Save".