Single instance of windows service querying multiple databases

My current situation is that we have four instances of a single windows service running on the server, for production, demo, QA and dev. I am looking for a solution where I just need to run single instance of the service that will hit all the above mentioned databases and process the data.

I know the purpose of having multiple databases (QA, dev etc.) is to do through testing and so I might have to install more than one instances. I am willing to install couple of instances (which is still less than 4 ) so that the maintenance is less.

But is there a way that a single windows service will do some sort of round robin technique and hit one database, do the processing, then hit the another database, do the processing and so on.