If tiddler A and B are from the same “type” you can create a tiddler C and transclude A & B into C instead of B into A. In this case C is needed to be the “summary” tiddler.
The transclude-widget has an option, that it shows it’s body, when the parameters don’t create a result. eg:
So the “outer” transclude widget shows the caption field, if it exists. If it doesn’t it shows the “inner” widget, which shows the title. We use this mechanism for the list-links macro and the table of content