Change formula based on results of vlookup

Greetings, Gurus.

This one is giving me a headache. Here's the deal,... the formula below will lookup a value, (net weight), based on a part number. It is tweaked to show blank if the returned value is #N/A or 0.

=IF(OR($S$3="",ISNA(VLOOKUP($S$3,npa,12,FALSE))),"",IF(VLOOKUP($S$3,npa,12,FALSE)=0,"", VLOOKUP($S$3,npa,12,FALSE)))*2.2

The "*2.2" at the end is used to convert Kg to pounds. The problem is, some of the weights are in pounds, (from domestic suppliers), and some are in Kg, (from overseas suppliers). If I have a list of supplier numbers, and this number is captured in cell K31, is there anyway to lookup this number to determine if the supplier is domestic or overseas, and then apply the correct formula based on that result?

I have named a table containing all domestioc supplier numbers "domestic", and all overseas supplier numbers "overseas". I was hoping I could lookup the vendor number, (cell K31), from these tables, and then apply the formula based on which table it was found in.

Since I'm certain this was confusing, (i've even confused myself), I've attached a sample workbook. The two cells bordered in thich RED are the cells containing the values. The sheet is protected, but no password is used.

Thanks in advance for any help you can offer.

Hutch