Two Collections inside a Composite View

So we are working on a project using marionette and we have made a good progress so far, but we struggling with a part of the marionette nested view model,

so lets assume that we have an apartment (represented as a composite view), and the apartment contains a collection of rooms and a collection of chairs, what we want to do is have the rooms and chairs a direct descending of the aprtment composite view, how can we do this, knowing that the composite view can only have one child collection, should we be using regions?