changing XREF1 & XREF2 for a Document No.

hi guys,

well i have come across this problem, what i need to do is...i have to change reference keys (XREF1 & Xref2) for a particular Document number, so any one can plz suggest me the best way to do it...well one way is by transaction FB02....can u suggest me any other idea??

Regards.

AMIT