Thanks for the quick answer. Now I understand I didn't asked my question correctly.
I know it is possible to do this, but I actually want to combine a qml into my .ui widget.
I finally found a tutorial for this (https://www.ics.com/blog/combining-qt-widgets-and-qml-qwidgetcreatewindowcontainer). It says it is only possible to do this from qt 5.0. For my embedded system I'm working with 4.7. So this isn't possible for me.
This is a Qt oriented forum and is not likely to be linked in any way to 'Viginia Tech'. I would recommend contacting someone over there.
If you have interest in C++ programming with the Qt framework then you are at the right place here.