Double dimmer on landing - single switch on ground floor - rocker switch - single switch on 2nd floor - rocker switch.
Dimmer on landing has 3 grey wires - 1 has black/red/nutrual (on loop) the other two have yellow/red/blue. Some wires will need to be double up but cant work it out. Which wires go into L1, L1 & C on both sides
On the 2 way switches it doesn't really matter as long as you use the same colours at both ends.
On the end where you have extra wires to go in put them on L1 and L2.
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