What is the best way to create a Parent/Child Relationship for SRs in HR Help Desk?

Summary:

We have a requirement from a client for the ability to create Child SRs directly from the Parent SR and the Child SR number should retain the parent SR # -1.

Content (please ensure you mask any confidential information):

Currently, the only way that we know to create a Child SR is to Copy the Parent SR, then go into the Copy and use the create relationship feature. This is multiple steps, and creates a completely new SR number that is not tied to the parent. Our Client would like the Parent SR to be SR1200, and the child SRs to be SR1200-1, SR1200-2 and so on.