This happened yesterday: I moved my Death Star core (Joan + Santiago KHD + 3 Hospitallers) with stealth through the ZoC (no LoF) of an Aleph repeater. I got Joan to a good firing position and shot the repeater. The guy playing Aleph obviously had AROs for his hackers because Joan was inside the repeater ZoC. The thing was that he chose not to hack Joan (who fired her weapon thus breaking stealth) but to hack my Santiago who was part of the fireteam and also finished inside the repeater's ZoC. Was this legal? I mean, he told me that Joan firing broke the stealth for the whole fireteam, not just for herself. It sounds logical but I'm not 100% sold on that idea and I couldn't find any reference to this kind of situation. Help please!
It was, all the fireteam declares BS attack (support skill), but Joan is the only who make the real attack with all the bonuses. As they are declaring something that is not a movement, stealth breaks for everyone. The only exception to this would be if the fireteam couldn't use the skill, then it's an idle (for example, the Santiago KHD using the repeater to fry the other hacker)
Note that Stealth is optional. You could say that Joan isn't using Stealth. Then, the Order Expenditure Sequence will look like this: Joan and other troopers move into the enemy Hacking Area. At this point, Joan is the only possible target for Hacking, as the others are using Stealth. The reactive Hacker declares a hacking attack vs Joan, or chooses not to react to the Order at all. Joan declares shooting (although Reset might be better). This gets resolved with Joan shooting the Repeater, and the enemy Hacker getting an unopposed hacking attack against Joan.