i merged the two threads as i saw the duplication. and noticed you also asked about the ipspace for that interface.
i think you can't change the ipspace of the Vserver object that hosts the MGMT interfaces (the cluster_name SVM) it have to stay in the default one.
i was looking at this years back and prtty sure it was not possible. also don't see it possible here (you can't change any SVM IPSpace post creation) :
i do encourage you also to have a read on this above DOC for the ipspace typical use cases. as it's very rear for someone that is not service provider to need it and can create some pain.....