Convert project items to Allowance Items

We need a way to take a BOM item and 'convert' it to be part of an existing allowance. We keep running into issues where an item should have been added to a misc. budget as part of an internal change order and instead was not. The ICO was approved and POs generated. We don't want to wipe the ordering information, but do need to move the item out of gen pop and into solitary confinement LOL for project cost purposes.