Calling a plsql function from a form customization

I am just learning form customizations.

We are implementing Escalations (of service requests) in an R12.1.3 instance. My business users would like the note from the SR that is of type 'CS_PROBLEM' to be copied from the SR to the Escalation Summary field in the Escalation form (JTFECMAN). I have created a global variable of XX_INCIDENT_ID in the SR form, and I am able to access this in the Escalation form. I have written a function that finds the 'CS_PROBLEM' note for the incident_id. I cannot figure out how to call this function and return the note to the Escalation form. Is this something that can be