Split/merge attributes as well as properties.
This should handle attribute associations during entity splits and merges, but won't work in CMB until it uses an operator to associate attributes on the server instead of just associating them on the client. See smtk/extension/qt/qtAssociationWidget.{h,cxx}
.
Update
After discussion, we agreed that CMB will send the relevant client-side attribute systems to the server for the duration of the operation. Then pqCMBModelManager::handleOperationResult
will ensure that associations in the client attributes match the modified/created model entities.