I have outlined in a post above how you can do this. I have been doing just this long before EW 7 and NDI became available in EW and it works every time. Currently EW 7 cannot send an NDI stream AND output to the screen at the same time. It CAN import NDI streams from several sources.
Download and install, on your main church projection EW computer, the small Desktop Capture utility from the VMix downloads site - Mac or PC versions are both free.
Run that on your EW PC and you will be streaming any of the EW screens you wish to pick up.
Use your NDI enabled video mixing software - Vmix, OBS (if that can pick up NDI) or other software, and you can pick up whichever of the EW screens you wish as feeds - all while using EW as normal - projecting to the main screen and third monitor as well.
The utility is only a tiny piece of software, downloads in seconds and all you see when it is running is a small bar telling you how many connections you have. That disappears when you start or use EW. It has no effect on EW usage.
I also use NDI to send the church services to our church hall and other places around the church.
I download and install the Free NDI tools from :
Grab an old laptop - does not have to be a superdooper machine - Install those tools and run the NDI Studio Monitor. If you have a wired or wireless network at the church that all your computers are connected to, that laptop will pick up any NDI stream from any NDI source on the network. Connect that laptop to a projector or large TV and you have your program streamed to another room, hall, mothers room or wherever you need around your church.