Is there a to get field text from parent tiddler from a template

Let’s say I have three tiddlers, including:

*Tiddler A
*Tiddler B

This is what My Tiddler A looks like:

{{Tiddler B||Template}}
tiddler-a-field: Tiddler A Value

Tiddler B looks like:

tiddler-b-field: Tiddler B Value

How would I get the Template tiddler to call a field from Tiddler A, instead of Tiddler B when I am viewing Tiddler A?

Ideally, I would like to call the field from Tiddler A when Tiddler B’s field does not exist.

Is TiddlyWiki capable of doing something like this?

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:

<$transclude field=caption><$transclude field=title/></$transclude>

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