Merging the results of multiple async loaders

The current app I have inherited is using Angular 1.x and angular-translate, which makes use of the static file loader:

            prefix: '/bundles/backend/js/global/translates/locale-cms-',
            suffix: '.json'

I need to load an additional resource /api/1/translations?lang=en (for instance using useUrlLoader) and would like to know if this is possible, as I cannot get it working (I am reading the docs, mind you)… Would I need to create a custom loader that awaits the result of both HTTP requests and merges the results or can this be done using the existing machinery?

Preferably, I would just like to tack on the .useUrlLoader bits and have two requests fire off automatically and have their results get merged without me doing much else than calling forceAsyncReload(true).

I did an initial POC using the synchronous .translations() API, which proved that using a sync loader followed by an async loader worked as intended; merging the results. This got my hopes up, but have not had much luck with the async bit.

Source: AngularJS Questions