Update Z field from BSIK into BSAK when closing

Hi,

I have created Z field in BSIK table using "Append structure" option. I also created identical field via same option in table BSAK. When I clear open item system "delete" that item in table BSIK and create identical item in table BSAK (BSIK - open items; BSAK-closed items), BSIK and BSAK have same structure because of this trensfer of open items from BSIK to BSAK during open item clearing. My problem - when open item is cleared and item is transferd from BSIK to BSAK my Z field is not updated by system. Is it possible to set this in customizing or is there another way to update this Z field in BSAK when someone clear open items - user exit, modification or ???.

Thanks in advance.

Sasa