Hello Jean,
I wonder if there is a business role concept in GRC AC 5.2 and 5.3.
As far as I know, Business roles are introduced with GRC 10.x.
Business Roles is a container which holds single roles, composite role and even business roles as well.
If you want business role to be part of business role, then its very much possible in GRC 10.X.
Hope this answers your question.
Regards,
Deepak M