(Answered) When is Battlefield Support use declared?

[Lanceman]

From the boxset rules:

If a Support Type is to be used, it must be declared during the Combat Phase of the turn it will be used. The player reveals their selection of that Support Type, but does not need to reveal all choices of that Support Type .

But when does that actually take place? Does it have to be done at the beginning of the phase, or can I declare it any time it's my turn during the phase? If the latter, do I have to declare it all at once, or can I break it up between turns (artillery strike this turn, bombing the next time around, etc.). Does the declaration take the place of me firing with a unit on my turn?

[nckestrel]

It must be the Combat Phase, and while you are making attacks with your units.
It can be in any order within your units attacking.  You can attack with one unit, then do a battlefield support attack, then two more of your units attack, and then two battlefield support attacks, etc.
You can't attack, even with battlefield support, during another player's attacks.  If you lost initiative and are making your attacks first, you can't do a battlefield support attack after your opponent attacks, you've already made your attacks.

Which battlefield support attacks you use each turn are up to you. You can use one, all or none in a turn. You can just use each once in the game.
They do not replace any other attacks by your units.