Accruals for Employees in SAP SF

Hello all,

I was wondering, can we make the accruals run automatically through the Manage Time off Calendar or any other type of accruals for a single employee or a few employees ??

my other question is: can we change the accrual total amount for a single user without changing the amount that has been used in the lookup?

for an example: the accruals amount for the user per year is 14 days, can we change the accrual amount for a SINGLE user to be 21 days instead of 14 days, without editing the lookup () amount ? because it will affect all users who has that time account type?