Automatic filling fields using BRF+

Hi,

I have a scenario in which i am creating a material with a change request YAT01 and material type FERT, while creating it I want system to pick few fields automatically for eg DISMM should be RE, DISPO should be abc  MTVFP should be YZ and there are few more fields from other table like MARA and MVKE which i want SAP to pick automatically

how can i achieve this using BRFPLUS, I do not want to go for IF ELSE condition, is there any other expression type which i can use and achieve this functionality

Thanks

Arihant