How to reference a field value on a parent table from a sub table form in the On Create trigger

Hi support,I have DB with a table named Claims, it has a sub table named PaySlips.  When I initiate add record for the PaySlips table (from the Claims form view), what is the syntax or required code to reference a field vale on the parent table ie the Claims table?

I’ve searched the User Reference doc and the support community discussions threads but can not locate anything to help me. I have tried many different ways but just can’t seem to get it working.