External Notifications into CUDA Asynchronous Loop

I have a CUDA application where I am doing some processing in a tight loop. I have a few different streams so that I can overlap Host to Device / Device to Host transfers with the processing. In fact, there are 3 streams - one handles the input transfers, one handles the processing, and the third transfers the processed device data back to the host. I use events to tell the processing when there is data ready to be processed, and vice - versa to tell the output stream when data is ready to go back to the host. That way I can synchronize the asynchronous stream calls.
There will be an external process filling up the host buffers with data so that it can be sent down to the cuda device. I need a way to notify an asynchronous stream that the data is there without destroying the concurrency that I have created within the cuda streams. Is there an easy way that the external process can create a cuda event that can be read by one of the cuda streams?
Thanks for your help!

These processes may have parent / child relationship if that allows them to share cuda events.