Without a little more detail, it's hard to say what the best approach is going to be (though I'm almost certain that you'll want to add/get the ID in the source data.)
What do you mean "showing the information to others"? Is it just a printout or they are looking over your shoulder? Or are you distributing the workbook to them? (in which case, an alias or calculated field won't work because they will be able to get to the underlying values).
What version of Tableau are you using?
In showing it to others it would be in print form so I have no concern about them seeing the underlying data.
I had created a formula in the past that worked in version 7. My first formula "Full Name" combined the two fields that had their first and last names "IFNULL(([Last Name]+","+" "+[First Name]),[Last Name])" I then created a second formula "Supporter ID" that assigned a number to each entry in the "Full Name" field. This had worked until I upgraded to 8. But since then any new entry does not get an ID. But the originals still have an assigned ID. When I open the formula it actually shows the same formula for the "Full Name" even though it is functioning the way it was created. So I cannot see how it was originally written.