yes i am doing this way, installing the qs server in a machine that has qv server installed
but as what i know, both qv/qs server can exist in the same machine, just that you can not run the services from both side at the same time
i have also installed both server program in the same machine before and it just worked fine
is that any official document saying that this action is no longer allowed for new versions of qs / qv?
Yes, there is.
Please see the link below. It's right down at the bottom of the page.