...
REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE("Physical Item Details"."Modified By",'902298925910135016','MHHN'),'915144202','LF'),'908663101','CDC'),'909413966','MRTL'),'915252914','MKD'),'910061693','CP'),'907604594','YL'),'915628432','HT'),'915802314','ARM'),'909818183','EL'),'915516216916241818', 'RAEC')
You can add replacement functions to this by appending ,'USERID','INITIALS') and prepending REPLACE(