You are still asking if it is possible - you are not asking how you would develop a solution to have a different number series depending upon teh customer group.
This is also teh technical forum not the developers forum.
It is possible - as standard you can define relationships btw different Number Series. And if displaying field “Posting No. Series” on sales-form (Order, Invoice, CRM, user is able to change. Take a look at the online-help in NAV.