Add a group to a module

<?xml version="1.0"?>
<objects>
  <object type="ModuleGroup">
    <id_module>274</id_module>
    <id_shop>1</id_shop>
	  <id_group>4</id_group>
  </object>
</objects>

It also posible to delete this link:

<?xml version="1.0"?>
<delete>
  <object type="ModuleGroup">
    <id_module>274</id_module>
    <id_shop>3</id_shop>
    <id_group>4</id_group>
  </object>
</delete>