I think you can create a subobject and then go to the Master Objects Views from Administration --> Studio --> Objects path.
Click on the "Layout - Edit" view for the master object and you will definitely find a row for the Subpage of that subobject.
Once clicked, you will be able to modify the name of Subpage as per your requirement. So I think rather that linking it to a different Subpage, you can rename the subpage (to "Mission Criticality") and achieve what you were looking for.
Hope that helps.
Thanks,
Abhisek Dhar