Change widget function in the child theme

Hello the team,

I’d like to modify the avia social count widget in order to add a Facebook link in my child theme.
I wrote in my functions.php :

function avia_socialcount ()
{
	class avia_socialcount extends WP_Widget {

		function __construct() {
			//Constructor
			$widget_ops = array('classname' => 'avia_socialcount', 'description' => __('A widget to display a link to your twitter, facebook profiles and rss feed', 'avia_framework') );
			parent::__construct( 'avia_socialcount', THEMENAME.' RSS Link, Twitter et Facebook Account', $widget_ops );
		}

		function widget($args, $instance) {
			// prints the widget

			extract($args, EXTR_SKIP);
			$twitter = empty($instance['twitter']) ? '' : $instance['twitter'];
			$facebook = empty($instance['twitter']) ? '' : $instance['facebook'];
			$rss 	 = empty($instance['rss'])     ? '' : $instance['rss'];
			$rss = preg_replace('!https?:\/\/feeds.feedburner.com\/!','',$rss);

			if(!empty($twitter) || !empty($rss) || !empty($facebook))
			{
				$addClass = "asc_multi_count";
				if(!isset($twitter) || !isset($rss) || !isset($facebook)) $addClass = 'asc_single_count';

				echo $before_widget;
				$output = "";
				if(!empty($twitter))
				{
					$link = 'http://twitter.com/'.$twitter.'/';
					$before = apply_filters('avf_social_widget', "", 'twitter');
					$output .= "<a href='$link' class='asc_twitter $addClass'>{$before}<strong class='asc_count'>".__('Follow','avia_framework')."</strong><span>".__('on Twitter','avia_framework')."</span></a>";
					
				}
				
				if(!empty($facebook))
				{
					$link2 = 'https://www.facebook.com/'.$facebook.'/';
					$before = apply_filters('avf_social_widget', "", 'facebook');
					$output .= "<a href='$link2' class='asc_facebook $addClass'>{$before}<strong class='asc_count'>".__('Follow','avia_framework')."</strong><span>".__('sur Facebook','avia_framework')."</span></a>";
					
				}

				if($rss)
				{
					$output .= "<a href='$rss' class='asc_rss $addClass'>".apply_filters('avf_social_widget',"", 'rss')."<strong class='asc_count'>".__('Subscribe','avia_framework')."</strong><span>".__('to RSS Feed','avia_framework')."</span></a>";
				}

				echo $output;
				echo $after_widget;
			}
		}

		function update($new_instance, $old_instance) {
			//save the widget
			$instance = $old_instance;
			foreach($new_instance as $key=>$value)
			{
				$instance[$key]	= strip_tags($new_instance[$key]);
			}

			return $instance;
		}

		function form($instance) {
			//widgetform in backend

			$instance = wp_parse_args( (array) $instance, array('rss' => avia_get_option('feedburner'), 'twitter', 'facebook' => avia_get_option('twitter') ) );
			$twitter = empty($instance['twitter']) ? '' :  strip_tags($instance['twitter']);
			$facebook = empty($instance['facebook']) ? '' :  strip_tags($instance['facebook']);
			$rss 	 = empty($instance['rss'])     ? '' :  strip_tags($instance['rss']);
	?>
			<p>
			<label for="<?php echo $this->get_field_id('twitter'); ?>"><?php _e('Twitter Username:', 'avia_framework'); ?>
			<input class="widefat" id="<?php echo $this->get_field_id('twitter'); ?>" name="<?php echo $this->get_field_name('twitter'); ?>" type="text" value="<?php echo esc_attr($twitter); ?>" /></label></p>
			
			<p>
			<label for="<?php echo $this->get_field_id('facebook'); ?>"><?php _e('Facebook Username:', 'avia_framework'); ?>
			<input class="widefat" id="<?php echo $this->get_field_id('facebook'); ?>" name="<?php echo $this->get_field_name('facebook'); ?>" type="text" value="<?php echo esc_attr($facebook); ?>" /></label></p>

			<p><label for="<?php echo $this->get_field_id('rss'); ?>"><?php _e('Enter your feed url:', 'avia_framework'); ?>
			<input class="widefat" id="<?php echo $this->get_field_id('rss'); ?>" name="<?php echo $this->get_field_name('rss'); ?>" type="text" value="<?php echo esc_attr($rss); ?>" /></label></p>

		<?php
		}
	}
}

But nothing changes in my backend, the function of the parent theme is loaded instead of this one of my child theme.

Please help.

Best regards.