CIC recommends combining or submitting together whole family application.
if you have applied few days before your wife and children,
I would suggest writing a letter and explain and provide client ids for both application,
they wount mind combining, unless they get confused. in fact there is nothing to confuse.
if you are hurry to get CITIZENSHIP then let the app. separate.
otherwise you can combine.
once you group you can not seperate.
you know what i mean, say one of them have RQ or test failing or anything, then until that is cleared.
it may not in your case but just in case.
my friend failed and hiis wife passed. that delayed total 8months . hahaha . you got my point.