1. Try to have qml file one directory, and all the file under that directory could be importable in any file on that directory, this is the first thing to know.
ie: mod{file1.qml, file2.qml}
2. In the parent directory you could have qml file, and you are able to load custom qml file under mod/ directory, like this the mod/ is the custom which is importable like this after import QtQuick 2.0, add import "mod".
3. That is it.