I am replacing a three gang rocker, with a three gang dimmer. Should be easy, because.......
The first is 2 way, so has 3 wires, a common, an L1 and an L2.
The second is 1 way, so has 2 wires, a common, and an L2.
the third is 1 way, so has 2 wires, a common and an L2.
Easy so far...