Manager approvals when a manager doesn't exist

Hi everyone,

We have a few catalog items in our Service Catalog that require an approval from a manager before the workflow can proceed.   On many of these items, we use the user table to look up the requestor's manager (we sync with Active Directory to get user data in) so the approval can automatically go to that manager.   Normally this works just fine, but we run into problems when a requestor doesn't have a manager listed.   In that case, the approval task gets "sent" to UNKNOWN (the value of the manager field in the requestor's user profile) and therefore can't be approved.   Furthermore, it doesn't look like the approval task can be reassigned to someone else once it's created.

Does anyone know of a quick way to redirect these approvals from UNKNOWN to an actual person?   Thanks!