[Mobhack]

That would result in the entire conglomeration being auto-bought by the AI, with absolutely no choice to the player. This includes human players as the battle group HQ is automatically bought as part of force selection.

And if the battle was low points, then the AI force would almost always be your home-made formation, or parts of it.

Naturally, some people have done such in home-made OOBs they have published in the past, and run into the same results.

The battle group HQ is therefore to consist of the HQ only. Anything else is silly - but go ahead if you want to, the option is there for anyone to use in their own home-made OOBs, give it a try. You will likely ditch it as soon as the limitations are brought to light.