Gudday to all XL gurus.

I need some help on using the SORT function.
I have a list of 100 competitors in a scoring spreadsheet that I have written.

I was trying to sort by surname (a-z). The problem is that this list is generated elsewhere and contains VLOOKUP functions. Obviously if i have less than 100 competitors I end up with some cells appear blank but contain VLOOKUP functions. XL sorts them first and I want them sorted last after the surnames (a-z). I cant add a helper column as this list relates to over 48,000 forumulaes and functions that are already added. If I add a helper column I have to re write all those formulaes.

I tried adding a custom list in the tools - options - custom lists but that still doesnt work.

ANY HELP WOULD BE GREATLY APPRECIATED

cheers and thanks guys/gals
CHAPPO555