You could install EW on each of the volunteer's computers and have them create the schedule for that week. They save the schedule to a flash drive or cloud storage such as Google Drive, DropBox, etc. making sure to check the "Pack files in schedule" in the save dialog box so that all of the media, backgrounds, etc. is saved with the schedule. Then copy or download the saved file to the church computer and open it. To save the changes and additions to the Church computer right click anywhere in the schedule and select the "Check Schedule for Changes" to import anything new to the computers database and/or update any existing songs.