How to change Validation message class/ID

Hi,

Currently, the message class configured in validation OB28 is using standard SAP message class /SAPDMC/LSMW_OBJ_080 but there is a new meesage class Z5 created, can anyone advise how to change the validation message class/ID in OB28 from /SAPDMC/LSMW_OBJ_080 to Z5?

Thanks!