What Simsy has suggested is a really good idea, I think. The sort will be fine so long as the entire range of data is selected to be sorted, with the correct column being selected as the sort criteria. Depending on how many people are being tracked will define how labour intensive it is to set up initially, but it will certainly work.
Maybe to help with ensuring the entire range is sorted without missing anything, if you select any of the populated cells and press Ctrl+a , this will select the entire range, so long as all the cells are immediately adjacent, and then it's just a case of doing a custom sort of the whole by way of the new column. This won't work if you select an empty cell before Ctrl+a, as that will select the entire sheet, so you must click on a cell with data in it for that to function correctly.