Lock On Modern Air Combat is the first game of the series which belongs to Ubisoft, after that there is all the Flaming Cliffs which belong to Eagle Dinamics and therefore you need the first one to play the Flaming cliffs, just a matter of rights ownership.
Eagle Dynamics has then built its own Sim World : DCS World and you can install modules in it, like Flaming Cliffs, which is now a module of DCS World, not a stand alone product (only this Flaming Cliffs3 needs LOMAC for module to work in DCS World).
So you can erase your LOMAC and FC3, install DCS World in your new PC and then install the modules directly from ED webpage and put in your code.
I did exactly that and then bought A10C, P51 and Combined Arms.
For me, the best right now.
Cheers