Hi there... a couple o thoughts or you. What you are asking for is not complicated. Adding a microphone to you existing setup should be pretty easy, BUT getting help here is going to be tough. You don't indicate your location, but you likely need some local help. Was the church moving on a positive parting? Could you contact them and ask their sound people for a bit of help? If that's not the case, then talk to a couple of the larger churches in the area and get in touch with their sound/technical team. I'm sure you could find someone to come over and help for low or no cost. Last option would be to find a production company and pay them to have someone come over and help with your system. I know I couldn't answer your question... but I hope this gives you a path forward.
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Kirk Longhofer
Theatrical Sound Design, Audio Production, Editing and Engineering
Systems Design and Consultation
www.technopraxis.orgkirk@technoprasix.org------------------------------