Hi Spike,
Thanks for the question! It is my understanding that a GCDQ counts as a CDQ for everyone who participates in the GCDQ, because they are all working toward the development for the same objective and can all benefit from it. In a normal (single) CDQ, you can invite other people to help you, but you are the only one who will benefit from a successful result. This is why single CDQs count for only one person.
Because they involve an entire group, GCDQs take a little extra planning. However, the effect of having so many characters working together means that great things can be accomplished on a GCDQ as well, certainly beyond the scope of a normal CDQ.
I hope this helps you figure things out.
Regards,
~Carillon