this is tricky and it’s not possible to my knowledge to do it both ways, just one.
There is way how to do it by insterting relays into the circuit, but I personally dont think it’s really good solution.
usual staircase switch does have master and slaves (can be more than one), master is not necessarily the one which physically switches light in question, this is something you need to know or figure out by current wiring.
The switch which is physically connected to the light will be your new main. Rest of them will be dummy, eg. connected ONLY to L(in) and N, eg. your L(out) will be not used on those.
for the wiring. I’m not familiar with Ireland regulations, but in EU since 2005 it is done like this
as you can see, only master is connected to L and carriing switchable L to the slave, which then closing the circuit, the third wire is carriing L back to the master switch when slave is used to switch light on.
in your new setup you will basically just need to use one L to bring L to the slave which will be used as master from now, and in former master just use L and N to power up your new switch.
And then you’ll need to switch slave and master ON by triggering rules, which I mentioned here.