I may be trying to achieve the impossible here. I have a source vserver that has a DP relationship from another vserver. I have created a SVMDR relationship on the partner cluster in second site successfully, but the DP volume from the source is excluded. If I break the SVMDR relationship and create the same volume on the destination, then I get an error saying that I need to delete it if I want to re-establish the relationship.
Unfortunately some sort of cascade or fan-out will not be available until 9.3 time frame.