Make node a revision of another node
I have not come across such a scenario. However, here's a fairly simple method to achieve it:


Install the Entity Reference module
Add an Entity Reference field to the content type of this node by navigating to Structure > Content Type > [the content type of these nodes] > Manage Fields
Choose the Target type as 'Node' &amp; choose the same content type as the 'bundle'
Label this field as 'Revision of' (say)
Now, you can either choose to manually enter the 'nid' of the original node here or run a query in the database to fill this entity reference field with the nid of the original node.
For example, lets say the content type is 'test' &amp; the entity reference field is 'field_revision_of'

6.a. Write an insert query like this:
   insert into 'field_data_field_revision_of' set entity_type = 'node',bundle='test',deleted=0,entity_id = [nid of revision node],revision_id = [nid of revision node],language='und',delta=0,field_revision_of_target_id=[nid of original node];

6.b. Since you should also update the database revision table of a field:
 insert into 'field_revision_field_revision_of' set entity_type = 'node',bundle='test',deleted=0,entity_id = [nid of revision node],revision_id = [nid of revision node],language='und',delta=0,field_revision_of_target_id=[nid of original node];


Let me know if this helps.

Regards,

Supriya Rajgopal