Child age validation on HRBEN0001(Urgent)

Hi Gurus,

We want to add validation on child age In on HRBEN0001 t code in  Enhancement pack EHP4 -SAP system.

When plan Dep child (Bplan- DPCH) is selected and if child age is greater than 26 then want to display error message

on coverage plan screen(Diouble click on dependent child plan) .Kindly let me know if any user exit,badi or enhancement is available .

Thanks,

Netra