Changing Mailbox From One Policy to another Policy

Hello,

I'm currently running exchange 2007 and Enterprise Vault 10.0.04.1189. I'm having four Storage Vaults for the purpose of having right staff/employees in the correct Storage Vaults. Each Storage Vault has different archiving rules based on the ege of items.

Low = items older than 6 months.

Normal = items older than 3 months.

High = items older than 1 month.

I have couple of users who are currently in High and their items are getting archived very soon and they requested to have it archived longer period which meant to me is to move them either to Low or to Normal.

Is there any precuation to take care of before I change their targets policy from one to another?

What the procedure to change an archived mailbox target from one policy to another?

Thanks,