Excluding function at user level of same reponsibility

Hi,

I have a requirement as below.

We have one responsibility Workflow Administrator Web to Check item key where we can retry and rewind any item key. Now This responsibility we have shared with our IT Team User so that hey can retry or rewind any item key.

  Now we have a certain user in the HR Department who want to create Vacation Rule for any employee. Now if i create the New responsibility and Add vacation rule Function to that responsibility then the user won't be able to access that functionality. When that HR user click on that function system gives error Only Workflow administrator can create the vacation rule. Reason for this error is, In Workflow Administrator we have set    'Workflow Administrator Web' responsibility.