Pass a Component into pushed StackView items

[sk2212]

Within a StackView I want to pass an Item (In this case a TabView Component) to pushed StackView Components.

So, the main question => How to pass a visual item into a QML component and be able to CHANGE this component within all QML components where it is used?

Something like this is working for non-pushed StackView items:

Item {
width: 100
height: 100
property var passedComponent
Item {
children: passedComponent
}
}

However, changing the "passedComponent" is only changed within same QML Component. Why? Is is not passed via "reference?