Can we use status 'Closed' instead of 'Finally Closed'?

Hi everyone,

I have two questions on PO control status:

1) I know status 'Finally Closed' prevents modifications to the PO.  Does status 'Closed' prevent the modification as well?  If answer to this question is yes, then,

2) The main purpose for us to use 'Finally Closed' is to unreserve the fund, especially at the year end.  And I think status 'Closed' won't unreserve the fund.  I just wonder if there is a easy way to unreserve the funds for all the PO that we like to close and then to use 'Closed' instead of 'Finally Closed'?

Finally Closed status gives us some problems since often we need to make changes (such as refund) after a few years.