Try this - this function can be usefull for blacklist and recip checking as well
PHP Code:
if (eregi($new_url, $old_url)) {do sth}
else {do sth else};
Please note there will be problem if someone submited
http://mydomain.com/freesite1/freesite2/freesite3/
and
http://mydomain.com/freesite1/
was already in DB
I see no point in creating such directory structure for free sites and I guess nobody does