What would be nice is a bit of linking material between the two - so that the GM can pull together an ACTA game thrown into the middle of a FS campaign (where a questing knight pokes his nose in the wrong place and a couple of raiders get sent to prevent him reporting back, for example).
A quick guide in terms of points sizes and ratios for quick/major and easy/hard encounters would be good.
Equally, some guidance for adding the player characters to a specific ship or fighter (and their effect on it for special actions, initiative, etc, and it on them - i.e. what trials and travails may entail for a knight and his marines trying to escape a ship wracked with various criticals).
ACTA can play pretty well multiplayer, so with a bit of guidance there's no reason it can't play well multiplayer-versus-GM.