So...an easy way to add a parent reference plus a straightforward way
to keep type creation links off the content/add page would pretty much
do it?
Am I missing something? Because the new node identification method in
4.7 can be adjusted slightly to hide those links. A small change to the
array hook_node_info() returns (add an element to indicate visibility),
a new op for _node_names() (call it "display create link" or something)
and a small change to node_add() would do it.
One thing that was a problem the last time
I looked was how to go about restricting access to node/add/[type that
requires parent]/[nid of parent] without other things breaking.
Previous discussions led me to override the menu settings to disallow
access to this path, but since the menu system does not prioritize it's
entries, you may find that your modification of the menu permissions
doesn't always work. The result is that the node/add page shows links
to add content that is not allowed to exist without a parent.