I have the following situation. I have a 'Basepage' document type from which I create child document types for each of my page types eg. 'homepage', 'genericpage' etc.
It's easy to find all children of a particular content node but what I want to do is find all children where their document type derives from the 'Basepage' document type.
So basically anything with a nodetypealias of 'homepage' or 'genericpage' etc.
This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/45500-get-all-published-content-where-the-document-type-is-a-child-of-a-specific-parent-document-type