Migrating child domains to a new forest in Active Directory

Hi all.

I just joined a company that has recently merged with another business. Business A, the new business, bought all of the assets of Business B, which included Business C. Bus. C will remain a valid business, but business B is now defunct.

Here’s the rub… In Active Directory, Business C is a child domain in Business B’s forest. In a perfect world, I’d like to “detach” Business C from Business B, and make C a child domain in Business A’s forest.
…With me so far? Both A and C are on Windows Server 2003 platforms.

ADMT 3.0 will do the job, but take a LOT more time, since the structure of Business C remains intact.

Any ideas?