Is there any way to get small artillery formations working? Currently when I try to drag my artillery formations onto another formation, it puts the artillery formation beneath it in the hierarchy rather than interpreting the drag as support. I think this is because the headquarters on my artillery formations are much smaller than those of the formations they should be supporting. Is there any other way I'm missing to set up the support properly? Or do I just have to make larger artillery formations to get the interface to cooperate?
Yes.
When the game is trying to be "smart", it does not look at actual formation size, it looks at the formations relative HQ capacity when determining which formation is the one thats supposed to be the artillery support.
So if you want a small artillery battery of 1000 tons to support an infantry company of 2000 tons, give the infantry company an HQ of 2000 capacity and the artillery battery an HQ of
at least 2001 ton capacity. As such, when you drag the artillery on top of the infantry to assign support, it'll work correctly.
It does mean that you are paying a little extra in unnecessary HQ capacity for the artillery but it'll allow you to assign really small artillery formations as support.