Branched user permissions for editing content types What is the best way to implement the user permissions (in brackets) in following pattern with Content Types as follows:


Parent (editable by owner &amp; tagged parent-editors)

Name
Description
...
Tagged Parent-editors (users)

Child (editable by owner &amp; tagged child-editors &amp; tagged parent-editors

Name
Description
...
Tagged Child-editors (users)
Entity reference: Parents

SubChild (editable by owner &amp; tagged child-editors &amp; tagged parent-editors)

Name
Description
...
Entity reference: Childs



Where "..." are some other fields, dependant on the ContentType.

Parent A editors must not be able to edit Parent B

I've looked into the Module Node Access User Reference which seems like it may do this potentially, but I was wondering if there is a standard way of doing this or whether anybody has some prefered/suggested Modules for doing this or even a completely different solution!
I think you may try Node Privacy by Role module.
First create three roles Parent Editors, Child Editors, Subchild Editors
Then while creating a node you will be asked about the permission to edit the node.
But this might not help you when you want to protect nodes per user.

There is also another module Taxonomy Access Control Lite which governs access to nodes based on the taxonomy terms applided to nodes.
In this you can create terms for Parent Editors, Child Editors and Subchild Editors

Apart from that there is also good discussion here:

http://drupal.org/node/24073

http://drupal.org/node/285369