react fragment

render() {
  return (
    <React.Fragment>
      <ChildA />
      <ChildB />
      <ChildC />
    </React.Fragment>
  );
}

//the same way you'd use any other element 
//except that it doesn't support keys or attributes.

render() {
  return (
    <>
      <p>Hello</p>
      <p>World!</p>
    </>
  );
}

return <div dangerouslySetInnerHTML={{ __html: yourStringWithHtmlInIt }} />;