You can lock down the whole sheet, by selecting all cells, then right click, and select FORMAT CELL. Go to the protection tab, and LOCK all of the cells.
Now go to the column that you wish to have them "click" on, and unlock those cells. Now go to the Main tab, and protect the sheet with a password. Now, it will only heck an x on unlocked cells. I am not certain how we can prevent "Mary" from checking on "Bob's" list, though.