Thanks for the clarifications. It should be possible to determine what you were supposed to get and hopefully the related information includes more than just an equipment list, although even that may give some indication. If it does appear that something was to be provided or accommodations made in the system then it sounds like this is too important an issue to accept it not being provided. In any case, knowing what was to be provided or if any provisions were made seems to potentially be a major factor in determining not just what solutions are possible and practical but also how temporary or permanent a solution may actually be required.We were under the impression that a box similar to our old one was in the sound schedule, and our principal says we are getting one, but the final walk through is on Friday, and we have had no word yet whether or not we are for sure getting one. To top it off, we have a church that has service in our auditorium every Sunday, and they have demonstrated to us that they do not know how to run sound. We've come back on Mondays to seeing all of the mic inputs and the main out on the mixer we used to have backstage maxed out, along with other things. This is why we don't want them anywhere near our booth. We are looking for more of a temporary solution than a permanent one at this point.
One thing to keep in mind is that if you start modifying a newly installed system that may be interpreted as not only accepting the work but it may also release the installer from some obligations, particularly in relation to any system warranty.
Perhaps critical to any discussion is knowing what the church and other similar users need. Is it a couple of mics and a CD player or is support for a full praise band with monitors? Is it practical for them to mix from the stage or might that actually be contributing to some of the problems you've encountered? Is a separate mixer with a portable snake practical or are they going to want to use floor box inputs, etc. that are hardwired to the house system? Can you limit access to the booth and new console and they still be able to turn the system on and off?
From a technical perspective, are there inputs to a system processor or similar other than through the new mixer? If not, is it feasible to leave the new mixer on and a couple of channels up or to train users to recall a scene on the new console (or can you maybe trigger that externally)?
I'm not expecting answers to all the questions noted, just trying to provide some general input that might trigger some ideas or responses.