Workflow Hierarchy

Hi,

I have following requirement, kindly let us know how to capture

1. EMP A

2. EMP B

3. EMP C

4. EMP D

EMP A create PO and gone for approval EMP B

If EMP B is not responded up to 5 days then workflow automatically should forward to next approver i.e. EMP C

If EMP C is not responded up to 7 days then workflow automatically should forward to next approver i.e. EMP D

If EMP D also not responded then PO should get approve automatically

Regards,

Madhu