Grouping tracks : is this how I do it . . .?

[xidnpnlss]

Oh come now we all know who’s responsible :

Octatrack Master Track 8 Send Effects

Nope, with T8 set as Master. But instead you can use a Flex playing a SRC3 Cue recording, real-time playback, choose Fx, and set each Cue Level as Fx send.