Email Groups on Hotmail/Outlook

I have created a new group but one of the people I want to add is already on another group email. Why can't I add this person's name to the second group? Surely I don't have to enter that person's details twice with separate group contact details?

I too hate the new Outlook/hotmail layouts. It is NOT self explanatory and I don't have the time or inclination to keep searching for what I was able to find quite easily with Hotmail.