Thanks for the help and the diagram.
I do have a couple of other questions on this,
Where is the 2 wire smoke zone on a omni pro 2?
And is it possible to use smokes with sounders, I would like to run 2 zones, 6 smokes on one and 4 on the other.
I am leaning toward the system sensor I3 with sounder and form c relay.
If one smoke detects trouble how do the rest know when wired on your diagram?