Hi Lorenzo,
I've assumed the following...

Sheet with concentrated data is named Concentrated
Column A heading = Pack or ID
Column B heading = Box#
Column C heading = Part ID
Column D heading = W.O
Column E heading = Qty

Sheet with new data is named New
Column A heading = Part ID
Column B heading = W.O
Column C heading = Qty
Column D heading = Pack or ID
Column E heading = Box#

The formula I used in Column D (Pack or ID) on Sheet New was...

=IF(COUNTIF(Concentrated!$D:$D,New!B2)=0,"NEW-assignID",INDEX(Concentrated!$A:$E,MATCH(New!B2,Co ncentrated!$D:$D,0),1))

The formula I used in Column E (Box#) on Sheet New was...

=IF(COUNTIF(Concentrated!$D:$D,New!B2)=0,"NEW",IND EX(Concentrated!$A:$E,MATCH(New!B2,Concentrated!$D :$D,0),2))

Ken Johnson