Can Group Approval be used in conjunction with other workflows?
Microsoft Office SharePoint Server 2007 provides solutions that support many possible workflows within the organization as well as Group Approval. For more information on supported workflows, see Help for each of those. However, Group Approval cannot share the same document library with other workflow solutions because it uses a document library exclusively. A separate document library needs to be created on the Team Site to use other workflow solutions. For more information, see Help for the workflows. In other words, even though you choose to add other workflows on the Customize My Approval page which is specified page of Group Approval, the added workflows will not work properly.