I think you have a wrong view of things here. Lubuntu isn't really a "different distribution". The different "flavors" of Ubuntu are all the same distribution,

I think you have a wrong view of things here. Lubuntu isn't really a "different distribution". The different "flavors" of Ubuntu are all the same distribution, they just differ in their default install and settings. If you remove lxqt from lubuntu, install kde you can morph it into kubuntu.