How to change the default OS user when adding a system in CEN?

Hello,

I'm trying to add a system to CEN via RZ21.  The procedure requires to input the password of the OS user (<sid>adm) on the monitored system.

However, the local <sid>adm user does not exist.  Instead, we use a domain user ID (domain_name\<sid>adm).  Also, the User Name field seems to be fixed or can't be changed.  Is there a way to make this field changeable so that I could input the domain? If it can't be changed, how can I add a system to CEN given this situation?

Thanks in advance.