These are NO detectors. No way to switch that.

I plan to put first floor 3 detectors on one zone, and 2 second floor detectors on a different zone. Since all wires on a given smoke zone will need to be wired in parallel (including the two supervised wires) I will need to put the eol somewhere. If I put it across the terminals of the supervised wires at one of the devices, and that leg burns open, then the panel will not see that eol. If I put the eol at the panel, and one of the legs burns open, then the panel will not see a closure from that smoke detector and go into alarm. If I put a resistor on each device (3 in parallel on floor1) then my total resistance would be way less than it wants to see (parallel wiring would drop it)

The panel came with 3.3k resistors which I am using on all other zones (doors, glass, motion, etc).

Unfortunately I don't have enough zones to give all 5 of them discrete zones.

I can give the Carbons (total of 2, 1 for each floor) discrete zones

I still need to buy 2 round ceiling mount Carbon detectors. Any brand model recommendations? I have 4 cond wire home run to each location