Is there a way to update bidirectional connections automatically when a new object is created?

Is there any way to establish an automatic bidirectional connection so that, for instance, `CreateProfilePicture(url: ..., profilePictureUserId: ... )`, not only automatically creates a new `ProfilePicture` (works today), but also updates the connected `User { profilePicture }` field (does not happen today)?

See https://github.com/aws-amplify/amplify-cli/issues/556#issuecomment-829159925.

> This is a traditional example, where each `ProfilePicture` belongs to one `User` and each `User` has one `ProfilePicture`.
>
> ```graphql
> type ProfilePicture @model {
> user: User! @connection
> }
>
> type User @model {
> profilePicture: ProfilePicture @connection
> }
> ```
>
> We want to use `CreateProfilePicture` and, supplying only the user ID and necessary data, and create *both* the `ProfilePicture { user: { ... } }` *and* update `User { profilePicture: { ... } }`. At present, only the former happens.
>
> How can we establish a bidirectional connection like this in AppSync?

Start with the linked Amplify CLI issue and the GraphQL schema example in this report. Investigate whether AppSync supports automatically maintaining both sides of this connection when creating a ProfilePicture, and document the supported configuration or confirmed limitation.

Written by the indexing model from the issue text.