Different flavours of useradd ?

[Michael S <newsmichael@bigfoot.com>]

Hi all,

I use debian now for two years on different systems.
To add a debian user to a certain group, I can remember that I used a 
very simple syntax of 'useradd' to do that:

  useradd <existing-user> <newgroup>

But now after time has passed by, on my current debian system (unstable) 
I found that this syntax is not longer possible. Instead I have to use 
the -G flag and provide the complete list of existing groups plus the 
new group to perform the same.

Does someone know whether there are multiple alternative packages, or 
has syntax changed over time?

Currently I am using the useradd command from package 'passwd' version 
1:4.0.3-30.9

Michael