Subcoupling Features
You can add a multiphysics coupling feature under another multiphysics coupling feature, by right-clicking the parent multiphysics coupling feature and choosing a multiphysics coupling feature from the Features submenu. The child multiphysics coupling feature cannot set the coupled interfaces; they are always the same as the parents. Therefore, they do not include a Couplings section in their settings. But the child multiphysics coupling feature can add contributions to the physics in the same way as an ordinary multiphysics coupling feature. The child selection is always a subset of the parent selection. If a multiphysics coupling feature is selected in the user interface, you can add children using a context menu or the Attribute menu in the ribbon toolbar, if the coupling supports any children.
Instead of a child directly you can also add a link to another multiphysics coupling feature. In this case, users have to make sure that the coupling types in the features are be equal.
For subcoupling features, The mph. syntax will give the parent scope in the same way as phys. does for physics features. To use feature scope for the subcoupling (that is, comp1.parent.child), type item..
When setting up selection filters for parent couplings you use a Multiphysics Coupling Filter feature, which takes the coupled physics selection into account. This is not necessary for the subcoupling feature because its selection is always a subset of the parent selection. Therefore you must use a Selection Component Filter feature in this case.