Hi,
Easy Profile does not do this natively but it is possible by creating a simple Plugin, you can follow these steps:
- Download our skeleton plugin (you can find it at http://docs.easy-profile.com/index.php/article/triggers)
- Install it from Joomla Installer
- Enable it from Extensions->Plugins
- Open file /plugins/jsn/skeleton/skeleton.php
- Remove sample functions: "triggerFieldAvatarUpdate" and "triggerProfileUpdate"
- Add a function like this:

public function triggerProfileUpdate($user,&$data,$changed,$isNew)

{

    if(isset($data['here_the_alias_of_your_field']) && !empty($data['here_the_alias_of_your_field'])){

        $value = $data['HERE_THE_ALIAS_OF_YOUR_FIELD'];

        /* HERE YOU CAN ADD THE CODE TO CHECK IF THE VALUE IS VALID */

        if($valid) JsnHelper::addUserToGroup($user, HERE_THE_NUMERIC_ID_OF_USERGROUP_VALID_MEMBERSHIP);  // if the value is valid then this add user to usergroup

        else{

            JsnHelper::removeUserFromGroup($user, HERE_THE_NUMERIC_ID_OF_USERGROUP_VALID_MEMBERSHIP); // if the value is not valid then this remove user from usergroup

            $data['HERE_THE_ALIAS_OF_YOUR_FIELD'] = ''; // if the value is not valid then this delete the value

        }

    }

}

IMPORTANT NOTE: This code is not tested and not supported, this is only for example purpose.

Hi

Thank you for all the help thus far.
One more question, the code as I have it at the moment adds the user to the required user group, would it be possible to set it up so that for example after it has added the user to group with ID 18 it checks to see if the user is also in group with ID 19 if the user is in both groups the system then adds them to Group with ID 20 as well