Addy,
Your problem could be solved provided the first column in your original
sheet is a KEY column, i.e. its values are not repeated and each value
uniquely identifies the record. In this case I assume that you are
using the same keys in the other sheets as well, in the first column in
every instance.

If this is the case, then the expression:

'Cutting or Slitting'!N2

can be replaced by

VLOOKUP(A2, 'Cutting or Slitting'!A:Z, 14, 0)

because N is the 14th column.

This way, your first formula would become,

=IF(VLOOKUP(A2, 'Cutting or Slitting'!A:Z, 14, 0)=0,0,VLOOKUP(A2,
'Cutting or Slitting'!A:Z, 10, 0))

With this technique, the other tables will not be sorted automatically,
but they will show the correct amount in every case, regardless of how
the original table is sorted.

Does this help?

Kostis Vezerides