Migrating Student Email to Existing Employee O365 Tenant - What to do with Student Employee

[ChrstphrM]

We have an existing tenant in which employees have outlook mailboxes.

Students do not currently have O365 Outlook email.
Students currently use gmail.

We want to move student email to O365.

A user who is both a student and employee must have a separate email account for each role.

A user has a single network login ID (X12345678) even if they are both a student and employee.

Can we set up two mailboxes for a single user in a single tenant?
How do we do it?

How do we handle login via SSO so a user can choose which mailbox/O365 account to use?

[#2]

To improve clarity
We have an existing single tenant.
Employees have outlook mailboxes in the existing tenant.
Students do not currently have O365 Outlook email in the existing tenant.
Students currently use gmail.
We want to move student email to O365 Outlook.
A user who is both a student and employee must have a separate mailbox for each role.
Each user has a single network login ID (X12345678) even if they are both a student and employee.
We are currently using SSO / DUO.

1. Can we set up two mailboxes for a single user in the single tenant?
2. Can the two mailboxes be in two separate domains in the single tenant?
• @college.edu
• @student.college.edu
3. If possible, how do we do do this?
4. Can we configure login so a student employee can pick which mailbox to use at 0365 login?

[#3]

You can only have a single mailbox per user, it's a 1:1 relationship.