Specifying type of list objects in the json-ld context

Working with JSON-LD, and trying to create a @context that can be external to the main dataset.

I am trying to specify that all elements in a list are of a specified type, something along the lines of this:

{
    "@context": {
        "ex": "http://example.org/",
        "group": "ex:group",
        "members": {"@type": "ex:individual", "@id": "ex:member", "@container": "@set"}
    },
    "@type": "group",
    "@id": "ex:mygroup",
    "members": [
        {"name": "John"},
        {"name": "Jeff"},
        {"name": "Jane"}
    ]
}

but, I cannot get the @type to 'stick', the resulting rdf does not state than John is an individual.

If declaring 'inside' the main part, like this:

{
    "@context": {
        "ex": "http://example.org/",
        "group": "ex:group",
        "members": {"@type": "ex:individual", "@id": "ex:member", "@container": "@set"}
    },
    "@type": "group",
    "@id": "ex:mygroup",
    "members": [
        {"name": "John", "@type": "ex:individual"},
        {"name": "Jeff", "@type": "ex:individual"},
        {"name": "Jane", "@type": "ex:individual"}
    ]
}

it works, but I would really like to avoid changing the main part of the JSON struct.

The obvious benefit is that I can just tack on a JSON-LD context to an existing interface, for example using a link header.

What am I missing?

Edit: It could be that I am hoping for future functionality as discussed here.