How do I create an additional outlook email account, keeping my current address and adding others?

The supported way to keep the current Microsoft account and add another sign-in address is to add a new email address as an alias to the existing Microsoft account.

What this does:

1. Keeps the same Microsoft account, with the same contacts, storage, subscriptions, and settings.
2. Lets a new email address work as another username for that same account.
3. Allows creating a new Outlook.com address or adding an address from another provider.

How to add another email address:

1. Sign in to the Microsoft account "how you sign in" page.
2. Select Add email.
3. Follow the prompts to either:
   • create a new Outlook.com email address, or
   • add an existing email address from another provider.

Important limits relevant here:

• An existing Outlook.com or Hotmail address that is already its own Microsoft account cannot be added to another Microsoft account.
• Microsoft does not support merging two Microsoft accounts into one.
• If a separate new Outlook/Hotmail account is created, that becomes a different Microsoft account rather than an additional alias on the old one.

If the goal is to use a different Outlook.com address in Outlook for Windows while keeping the current account, a practical path is:

1. Add a new alias to the existing Microsoft account.
2. If needed, set that Outlook.com email as the primary alias.
3. In Outlook for Windows, remove and re-add the account.

If a completely separate mailbox is preferred instead of an alias, Outlook for Windows can hold more than one account or more than one profile:

1. Open Outlook.
2. Select File > Add Account to add another account.
3. Or create a separate Outlook profile:
   • Hold Shift while starting Outlook, or run Outlook.exe /profiles.
   • Select Options > New.
   • Name the profile and add the email account.

If a new Microsoft account is created, old account status, points, purchases, and legacy status do not transfer between accounts.

References:

• How to add an email address to your Microsoft account | Microsoft Support
• Outlook.com email account appears as "outlook_[long series of letters and numbers]@outlook.com" in Outlook for Windows | Microsoft Support
• Add an Outlook.com or Microsoft 365 account | Microsoft Support
• Create a profile in classic Outlook for Windows | Microsoft Support
• How can I transfer my current free Outlook mail to a new account without losing my perks or legacy status? - Microsoft Q&A
• Changing Microsoft Account Email - Microsoft Q&A
• How do I merge an existing microsoft account with a new one. - Microsoft Q&A