In the DMN editor, when you set up two chained DMN tables, and you go to edit the root decision node, the expression editor will autocomplete with the child table’s name.
e.g., if you set up Child → Parent
and then you edit Parent, create an input column, and edit the expression, it will autocomplete the value “Child”.
Which would be great, except that what you need in there is Child’s ID, not its name. The id doesn’t autocomplete.