Nested mutations

[JakeIwen]

I have made a GQL 'Activity' model. I want comments, bounces etc to be associated w/ an Activity when they are created. Looks like the answer is Nested mutations (Yes, it COULD be done via BT-API, but thats more room for error) .

https://www.graph.cool/docs/reference/graphql-api/mutation-api-ol0yuoz6go/#nested-create-mutations

Problem is, I cannot find the code of ours that is analogous to this:

I see how making a nested mutation might be possible using fetch() like we do in our API,
But is there a way to create both Bounce and an Activity mutation at the same time? Preferable within a JS Relay.mutation Class?

@carlpeaslee