Hmm. I thought #43 covered #66‘s notion of “repeater fields”. Every CMS/datamodeling tool calls them something else, but the core is the same: a structured, re-usable group of fields that don’t pollute the primary relationship namespace. They’re often identical to standard models under the hood (i.e., just another relation), but not exposed as such in the UX/API. I’ll drop a comment over there.
The way I read this request, it sounds like the concept of singleton models, where you can add specific fields to a particular instance of a type (or types that only allow one instance). Is that correct, @Erwin Otten? Some CMS’s call those Landing Pages, Single Pages, or some such, but they’re basically a one-off model that you can use to design specific pages and whatnot.