More than one command squad?

[son_of_volmer]

Is there anything disallowing someone to field multiple command squads?

[This Dave]

Nope, unless for some reason the Detatchment you're using only allows a single HQ choice.

[son_of_volmer]

Why is it restricted by the HQ slot?

Command Squads fall under Elites (at least in the Blood Angel dex). Shouldn't it be possible to fill all the Elite slots with Command Squads?

Is there a rule that states that a Command Squad can only be selected to go with an HQ?

[Da Gargoyle]

I think This Dave took your original question to mean that you were talking about HQ choices which is what command squads suggested. However, assuming your army is not unbound, you would be obliged to follow the force organisation chart which usually includes limits to HQ, Elites or whatever.

So the general answer is, if you follow the Org Chart then the number of command choices is limited by what ever section of the chart they belong to. For example Astra Militarum have Platoon Command and Company Command squads. PCs are part of troops choice but must belong to a platoon. CC are HQ and would be limited to 2 choices in the standard set up. If your BA options are Elites (?) then you get however many are allowed for that slot. What you can't do is allocate a unit that classifies as HQ to the Elite slot and your Codex tells you which belongs to which slot.

See pg 116 to 122 for the set up rules.

Of course, if your army is unbound then the issue of FOC slots is moot and your selections are limited by points cost. I imagine you would still have to nominate a Warlord though.