Proxy Domain Filter Wildcards

I have an NT Domain where all users access the internet through a Proxy Server. I have configured the filters to deny all sites except those included in the filter. This works fine for all sites such as www.123.com and www.123.abc.com. The website www.123.abc.com does not have to be specifically entered into the filter due to the appended "abc". The problem is many sites add servers by prefixing such as www.abc.123.com versus www.123.abc.com where www.123.com is the home site. By prefixing, the specific site has to be included in the filter. Adding specific IP addresses doesn't work. Is it possible to allow "prefixed" websites by using a wildcard in the prefix of a domain name in the proxy filter such as www.*.123.com? I tried it but no luck.