KO

I am trying to find out how I can have the same contacts in more than more group in my hotmail Outlook.  I know how to add a member to the group, but don't seem to be able to add the same person to several groups.  For example, if I want John Smith in my "Friends" group I can add him no problem.  I also want him to be in my "Football team" group, so follow the same process and add him to that.  However, when I then reopen my "Friends" group John Smith has gone.  It seems he can only be in "Friends" or "Football Team", but not both?

Can anyone help me work out how to get a contact into 2 or more groups?