Ok not the end of the world, 2 ways to sort this...Used Kentec sigma 2 wire panel, if using apollo smokes change bases to apollo sav, use all standard call points and smokes. and finally wire sounder reverse polarity. Second way change panel to CTEC or Kentec Alarmsense and change all devices to Alarmsense........the first is cheaper, using detection you have....but both will run all on 2 wires.
quick Kentec diagram to help.