How add custom node in a View (Nested View)?
You can use the Views Field View to show the Nested Nodes (that should be a kind of Node Reference)


  There are a lot of cases in views where you want to embed a list
  inside each row. One example could be, you have a list of groups, and
  for each groups you want to list the first and last name of all of
  their members.


For modify the content of a node you can use the template_preprocess_node() maybe you will need to Check content type of node in preprocess hook.