Have you found a solution yet?
I looked at the two links and am not sure, if that's helping?
Just like OP I need something like showing randomly 5 questionGROUPS out of 7.
As I understood, the first link is on question-level and not on group-level. If I try something similar on group level then it says something like "Variable not declared until a later page"...
The second link is on group-level but only handles getting ONE out of x groups. I think the simple "random1"-questionblock doesn't help in this case, or does it?
Am I right with those assumptions? If so, does anyone have the solution for our problem? If not, would you mind explaining it to me once again?