I'm looking for a way to select the faces of mates. I would like to create a virtual "reference geometry" part in a sub assembly to be able to fully define component locations in the sub. Currently we have flexible sub assemblies and individual parts mated at the top level. This is not a very robust design. Ideally I would like to select all of the mates out of the feature tree at the top level and then offset surface a distance of 0 the faces which the sub components are mated to. I could then mate all of the components in the correct locations to the reference geometry in the sub assembly and make it rigid in the top level.