Office 365 merger and acquistion- Company B would like to keep their old domain for emails


Hi All ,

   We have currently purchased a small company who's been using Google workspace and this is the scenario we have .

Company A = Parent company which is currently using Microsoft 365 (

Company B = acquired company which is currently using Google Workspace (


Now the requirement here is , company B would like to continue to use their current domain(i.e. for sending and receiving emails and they don't want their email address in Office 365 to have in it due to some specific business reasons . While this can be achieved by changing the primary SMTP address I guess the sharing emails alerts , teams invite email alerts and all other Office 365 alerts would still reflect the primary domain (i.e. company ) right ? Is there a way to get around that ?  They would be logging to our Office 365 tenant using the UPN )i.e. Email address removed )but they want the email to be sent and received using their companyB email address . 


So could someone help me with all the steps required to achieve this and I'd also like to specifically know if there's a way to tweak the sharing email alerts , teams invite email alerts because as per me they would still be showing .

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