How to make galleries relative to particular nodes?
The simplest way: Use colorbox module

In the structure of the content type add an image type (with multiple values allowed) and put its display type to be a colorbox gallery

The complex way: use view slideshow and computed field

Still add an image field to the content type, but set its rendering to hidden. 

Add a computed field with the value equal to the node nid and the display a view that take the node nid as contextual filter and render the image field using the slideshow plugin.

Set the display of this computed field as unsanitized.

Computed code:

if (!$entity-&gt;nid) node_save($entity);


Display Code (PHP):

$display_output = views_embed_view('&lt;your view name&gt;','&lt;your view display name&gt;',$entity_field_item['value']);


You can get an example here: http://agriregionieuropa.univpm.it/content/event/test-antonello (tab "video ed immagini").

The video slideshow uses the second approach (in this case videos, in your case photoes, it's the same), while the photo gallery uses the colorbox approach.