How can I change the partition Dimension in RDF?

Hi all,

How can I change the partition dimension on an RDF global domain? I've done the "Adding New Dimensions to Hierarchies" process before, but never had to do this. I want to lower the partition dimension from Group to Department.

COMPANY
DIVISION
GROUP	<== from
DEPARTMENT	<== to
CLASS
SUBCLASS
PARENT
ITEM

Of course, I have several measure in the domain that currently exist at the Group dimension and others that exist at the Department dimension.  Is this a complete domain rebuild? Can anyone shed some light on how this can be done? Any help greatly appreciate.

Thanks!