Hi @thansmann,
This has been tested locally, but whichever you prefer. Spiff will merge any value from the "right," it doesn't have to be an explicit merge. See https://github.com/cloudfoundry-incubator/spiff/blob/master/examples/tutorial.md
Actually, the `~` used to be `(( merge ))` but that broke if the tiles config wasn't specified further downstream. I guess `(( merge || nil ))` helps with that?