Permissions problem

I have a permissions problem with Apache but I am sure it is simple to cure.

Originally had 3 domains, all belonged to same user, so all webdirectories
were off the single home directory of that user:-
/home/user01/domainone.com/html/
/home/user01/domaintwo.com/html/
/home/user01/domainthree.com/html/

I simply set in httpd.conf the following:
User user01
Group user01

Now I want to have 3 individual linux users, each running one of these
domains off their own particular home directory:-
/home/user01/domainone.com/html/
/home/user02/domaintwo.com/html/
/home/user03/domainthree.com/html/

Problem is Apache will only show user01's website and refuse permisssion to
the other 2.

Can I make group in httpd.conf to something like webusers and then make all
users members of that group?
User user01
Group webusers

Cheers

Phil