Search on Addressee field?

I am having difficulty creating a Customer search based upon the Addressee field.  Our Customer name sometimes includes a company name and at other times is last name, first name or first name, last name. This means I cannot search on the name field top create a mail merge.  The only field which has the correct person's name in first name, last name order is the Addressee Field but this doesn't come up as an option in the search filters.