ya definitely this is the case....i'm currently working in an accounting firm and attending an interview with other firm which my gf currently work with, 1stly i duno that i will be allocated same department with her, but once i know the interviewer's name who is going to interview me, he is a manager from my gf's department....so means that i probably will be allocated to same department with my gf if i pass the interview....

so do i need to inform the manager regarding this matter during the interview?

I'm fresh grad (my gf oso), interviewing for audit associate position...