Strategy for testing interactions between 2 android apps

I have recently gotten started on testing our application with Appium that has capabilities to pass data/files in between itself and others (like dropbox, box, googledrive etc.).

My initial strategy was to launch my app I am testing, then to launch the cloud provider app to pass a file into my application.

I would launch my app as the AUT, and login, then try to launch another application like this:

This worked great, until the other application stopped allowing me to start the application after an update. I have the activity right, but the other app just launches and sit in the background. I realize how fragile this will be as the other applications update on my device, their could be a lot of instability.

So I have 2 questions:

  1. Is there a simple “launch this app I have installed on my phone” without having to define the activity?
  2. Should change my strategy to launch the cloud provider app as my AUT and then launch my application with the driver.start_activity method?

Any thoughts or ideas would be appreciated.
Thanks guys, love everything I have seen so far with Appium!