how to make URL aliases of nodes created via form include node title of original page?
try the Pathauto module:


  The Pathauto module automatically generates URL/path aliases for
  various kinds of content (nodes, taxonomy terms, users) without
  requiring the user to manually specify the path alias. This allows you
  to have URL aliases like /category/my-node-title instead of /node/123.
  The aliases are based upon a "pattern" system that uses tokens which
  the administrator can change.


Once set up, you can have it assign the path based on the title of the current node (X) and the field value you assign to the title of node (Y).  If you are using nodetitle or something to automatically assign the title for node (Y), you will have to run some custom code when content type (Y) is created in order to assign its alias.