How to redirect Service Portal users to another external ServiceNow Service Portal

[chrish5]

Our internal employees access our ServiceNow Service Portal by going to https://ourcompanyname.service-now.com/sp with SSO.  We are now migrating to our parent company's ServiceNow instance and will be using their Service Portal.  How do I redirect our employees that at going to https://ourcompanyname.service-now.com/sp to https://parentcompanyname.service-now.com/sp.  

[Dr Atul - LNG]

HI @chrish5 

In Xanadu release it is available OOTB, but before version you need to do scripting. 

[chrish5]

Hi.  Unfortunately, we are on Vancouver.  How and where would this be scripted?