[kainite311]

So if you fork either of these matrix actions to 2 devices in the same PAN/WAN/Host, do you get 2 marks on the "master"? Risk aside, which can be mitigated if properly set up (not relevant to current question though). As far as I read, the marks flow to the master in the PAN/WAN section of core.... But no mention the other way.

[Stainless Steel Devil Rat]

So if you fork either of these matrix actions to 2 devices in the same PAN/WAN/Host, do you get 2 marks on the "master"? Risk aside, which can be mitigated if properly set up (not relevant to current question though). As far as I read, the marks flow to the master in the PAN/WAN section of core.... But no mention the other way.

I suppose you can read it either way:

You get a mark on 2 devices, both flow upwards, so YES!

Despite getting a mark on 2 devices, it was still one action (where you presumably didn't take the inherent penalty for going for multiple marks), so NO!

I'd lean towards "NO!" from a game balance point of view.  It just feels like an exploit.  (and I get that's totally what hacking is, but you're supposed to hack in-game, you're not supposed to hack the rules!)

[Hobbes]

Balance-wise it rarely matters.  Additional Marks on a Host after the first are just for funnsies.  And, unless you're in combat passes, more Marks on a PAN Master is just an additional action. 

Letting Fork work to get you multiple Marks on a PAN master does devalue some of the "Go Big or Go Home" and similar PQs.  And possibly if you're Edging the roll it's more efficient as the Hacker essentially gets to Edge each roll.  But, usually getting Marks on non-Hosts is pretty trivial difficulty for a Hacker character. 

But I do think it's RAW.

p. 246 CRB from the Fork description: "Determine the result of the actions separately against each target."  Get a Mark on Slave Device #1, get a Mark on the PAN Master.  Get a Mark on Slave Device #2, get a Mark on the Master. 

[Jack_Spade]

It's RAW and it really doesn't devalue anything: After all, you have to load Fork and be ready to be marked or matrix damaged twice in return as well.