RZ20 error message to be displayed on SRM Portal

Hello Gurus,

     Can you someone provide me the idea of , how to display the error message of RZ20 on SRM Portal. We want to display the error message BP603 PO *** Item 001 Order **** budget exceeded.

I want this message to be displayed on the SRM portal . Basically I want to do the validation for both SC as well as PO. I checked the DOC_CHECK_BADI and its already Z implemented . Please do find the attached screenshot.

Thanks

Gaurav