What it says on the tin, BS Attack is a Support Skill and so is Discover, and fireteams cannot chain two of those. Now, it might be intentional, its definitely crystal clear how the rule is written, and there's a fireteam update coming sometime before 2099, but might as well ask.
This thread pretty definitively discusses the different interpretations. https://forum.corvusbelli.com/index.php?threads/38948/ Tl;dr in N3 it was FAQed so you could.
It must either be that "CB's authors are creatures of bad habit" or that "IJW said follow RAW to a fault". Either statement is surprising for the forum's Mod to endorse. /s I have NFI, but it's up there for ambiguous pronouncements in a forum known for them.
