I'm with the parishioners on this one -- they paid for the church facilities so I believe they own the church facilities.
There is already legal precedent (California, I believe) for a local church to leave the parent congregation and keep their property. And, I believe that there is conflicting case law (not sure of the state).
This will be an interesting case to armchair quarterback.
Here's a SCOTUS decision worth reading on the subject of the power of courts over hierarchial churches.