What do you mean by "link an Office 2019 Home&Business to a different account"?
Do you mean that you would like to link another account to your existing Microsoft account?
If so, per my research, to increase your security, currently Microsoft has retired that feature so you may not be able to link a Microsoft account (even with separate email addresses) or a non-Microsoft account (such as a Gmail account) to an existing Microsoft account.
Besides, if you want to change how you sign-in or how your name appears to people, you can add an alias to your existing Microsoft account.
Any misunderstandings or updates, please let me know.
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