My theme already has a [testimonials] shortcode

If you want to use Testimonials Widget's `[testimonials]` shortcode in a theme that already has that shortcode, no problem. Find add_shortcode() in your theme's source, copy that line to your child theme's functions.php file, but replaceadd_shortcode with remove_shortcode. Viola! No more theme shortcode preventing Testimonials Widget's from working.