What is best practices for such scenario in Workflow?

Question

I have one workflow which is calling a WCF service for some operations in my Library management application. Now one of the operation is to - to add a new book in the library. But if there does not exist an author in the database then it will first add author in the database, followed by adding a new book. Currently I have written them in single WCF operation (method), and calling it from Workflow activity. However, I would like to know if this is the best practice? or if I need to separate this task into two activities under same workflow