Ok
So 95% of people who use Office365, bascially register for 365 which in term creates a default AzureAD created in their main Azure subscription. Designated Global Administrators are then created within 365 which mean they have total un restricted access to all office365 admin portals as well as all users within that particular azure directory.
Now a days you can create multi azureAD directorys from the Azure Portal and sync from multiple environments using multiple copies of AADConnect.
So the question is, if i have a customer that started with AzureAD and setup directory sync as they required to use MFA and the gallery and didn't use 365 to start with. And now they want to extend services and use 365. Can enable this and create a 365 tenancy and link to the already existing AzureAD?
Cheers