FC has no Command ratings; there is no overt rule stopping you from taking as many ships (of whatever class) as you like.
That said, if players in that game want to follow the "historical" command structures, the best recommendation is to turn to the setup you see in the likes of SFB and F&E. (In the latter case, the issue of each unit's command rating is crucial; no matter how many ships you deploy into a given hex on the strategic map, the amount that can actually take part in a given battle force is restricted based on various factors, not least the flagship's CR value.)
It's in those games where the likes of the D7C, C7 and C8 are so notable, in terms of their increased command-and-control facilities. As you can see in this Klingon Ship Information Table for F&E, the CR of the D7C is 9 (as compared to the D7's 8), while the C7 has a CR of 9 and the C8 10. These values are exactly in line with their equivalent units in Star Fleet (where the CC, BC and DN have CRs of 9, 9 and 10 respectively).
Had there been no use for a command bonus in ACtA:SF at all, it wouldn't matter; but since the effort was made to put it into the game, it's not in keeping with the source material for the likes of the D7C to provide a higher command bonus than the C7. Not least since part of the whole point of the C7's construction in the first place was to act as an improved command platform (which, while more expensive than a D7C, was still cheaper than another C8).
That said, if players in that game want to follow the "historical" command structures, the best recommendation is to turn to the setup you see in the likes of SFB and F&E. (In the latter case, the issue of each unit's command rating is crucial; no matter how many ships you deploy into a given hex on the strategic map, the amount that can actually take part in a given battle force is restricted based on various factors, not least the flagship's CR value.)
It's in those games where the likes of the D7C, C7 and C8 are so notable, in terms of their increased command-and-control facilities. As you can see in this Klingon Ship Information Table for F&E, the CR of the D7C is 9 (as compared to the D7's 8), while the C7 has a CR of 9 and the C8 10. These values are exactly in line with their equivalent units in Star Fleet (where the CC, BC and DN have CRs of 9, 9 and 10 respectively).
Had there been no use for a command bonus in ACtA:SF at all, it wouldn't matter; but since the effort was made to put it into the game, it's not in keeping with the source material for the likes of the D7C to provide a higher command bonus than the C7. Not least since part of the whole point of the C7's construction in the first place was to act as an improved command platform (which, while more expensive than a D7C, was still cheaper than another C8).