Would that be good idea to promote 9 member group?

I mean I think if liked the group as a whole I'd been into this.

Subunits to show off members better, 2 group cbs a year... if you have the money then this is a great schedule imo

This may just be me, but I prefer groups to be around for more than a year or two to promote before subunits because if I was a CEO I wouldn't want to create an Orange Caramel and After School situation. I still like the idea that you have because it gives the group necessary breaks.

What would you do if the 5 member sub unit sells a million albums and tops the charts, while the full group and 4 member subunit does not even chart?

I think it's better if the first two years used for promoting the group first. You know how easy fans turn into akgaes so it's better to strengthen the group's popularity first. And I think not many company want to do it because if the subunits become very popular than the group's own released especially if they're still rookie it's done for everyone else in the group and those who in the subunit will be overshadowed everyone.