mh-omega-footer.php

<?php

/*
Plugin Name: Customize Footer on Omega theme and it's child themes
Description: This plugin hard codes a new footer into the <a href="https://wordpress.org/themes/omega/">Omega theme</a> and any child themes for Omega.
Version: 0.1
*/

add_action( 'after_setup_theme', 'mh_footer_setup', 21  );

function mh_footer_setup() {
    // Add new footer a via a filter
    add_filter( 'omega_footer_insert', 'new_default_footer_insert' );
    // Remove old footer via the same filter
    remove_filter( 'omega_footer_insert', 'omega_default_footer_insert' );
}

function new_default_footer_insert( $settings ) {

    return '<p class="copyright">' . __( 'Copyright &#169; ', 'omega' ) . date_i18n( 'Y' ) . ' ' . get_bloginfo( 'name' ) . '.</p>' . "\n\n" . '<p class="credit"><a class="child-link" href="https://en.wikipedia.org/wiki/Mars_Attacks!" title="Tom Jones was in it!">Mars Attacks!</a> was a fun movie</p>';

}