Password recovery using alternative email address

Hi,

I am in charge of a school, having one tenant. The tenant includes both staff and students.

I have enabled Password reset (SSPR) for a selected security group (containing all staff) to use their mobile number to reset their Office 365 password. I logged in to Microsoft Entra, went on Manage > Password reset > Properties, Enabled it for 'Selected', selected the security group and selected Email and mobile phone. It works for all staff that are members of the selected security group.

Now, I would like to enable SSPR for students using an alternative email address. All my students are grouped in one security group.  So I went to Password Reset > Authentication Methods, clicked on Email OTP and enabled it for 1 group containing all my students.

When I login to myaccount.microsoft.com and click on Security Info, when I click to add a sign-in method, I am NOT having 'Email' in the method pull-down menu:

May I please ask what am I doing wrong? My objective is to have mobile phone for staff SSPR and email for students.

Is it supported by Microsoft in the first place?

Please help

Thanks