I'm not sure this is what they are asking about, but perhaps a similar (if not equal) use case would be to set up a mapping with one set of values, then give the ability to clone and modify that mapping more easily.
For example, say I have a GET (order) happening that returns a JSON object for a particular URL. The JSON object is rather large, and I want to modify a subsection of the JSON (perhaps a zip code) while not touching all of the item / payment data. Currently, I would need to maintain a unique instance of each request locally to push up to WireMock (or set them up individually). That way if I have to change something about the base JSON, I need to modify every request.
But if there was a mechanism to say do the equivalent of geting mapping X, take the json, modify it to switch out the address / zip code, then republish the mapping to create mapping Y, but doing so in more of a PATCH type operation.