There are basically two possibilities. As the FBC tuner only has two physical inputs, you're limited to that. That means you either just use the two inputs with automatic assignment, like you do with directly connected tuner or a DiSEqC setup. Or that you re-arrange the transponders in a way that all transponders you want receive are on the same cable, that is what SCR (Unicable, JESS) is all about.
So either you have the automatic assignment, which means you'll have one (or two, depending on how many inputs are physically connected) transponders guaranteed and up to eight transponder if you're lucky (same quadrant).
Or you're using SCR and you'll always have eight transponders available.
SCR and DiSEqC are mutually exclusive by design. Aside the fact they're using similar signalling techniques may confuse each other.
If you want the full FBC functionality (eight independent tuners), you'll have to invest in a SCR switch or SCR LNB's. The latter seems to be a lot cheaper, but also has some drawbacks.