Sitecore 9 update 1 is there a way to mark
Azure AD group as Sitecore administrator without creating new Administrator group in Sitecore?
Assuming you have configured federated authentication properly. You can do this by mapping claims. This is an excerpt an example from @Bas Lijten 's blog.
As the Administrator role isn’t a real role, but more a Sitecore user property, this “role” needs to be set in a different way. The Propertyinitializer can be used to achieve this. First, it reads a claim (and its value) and if that claim has the defined value, the property will be set:
<propertyInitializer type="Sitecore.Owin.Authentication.Services.PropertyInitializer, Sitecore.Owin.Authentication"> <maps hint="list"> <!--The mapping sets the Email property of the user profile from emailaddress claim--> <map name="email claim" type="Sitecore.Owin.Authentication.Services.DefaultClaimToPropertyMapper, Sitecore.Owin.Authentication"> <data hint="raw:AddData"> <!--claim name--> <source name="idp" value="Auth0" /> <!--property name--> <target name="IsAdministrator" value="true" /> </data> </map> </maps>