Expense Payment Site Name need to add new for Payables

Dear,

we are try to create the some emplyee as a supplier and when I create the employee as a supplier then sytem give us only three selection option for the site Name "Office","Home" and "Provisional" which is not editable but when we create simple supplier then we have option to put the site name manually . It's possible we can add more site name or change the site name during the supplier creation as a employee and it will be not effect any where.