3 gang switch with 2 live source and zbmini L2

i have 2 questions here.

  1. how to power up zbmini? power up only without connecting to lamp.

  2. my original manual 3 gang switchs come with 2 live source. my house is on 3 phase circuit.
    but sonoff 3gang switchs only have one L in and 3 Out.
    i cannot combine both live line as it will tripped my DB.

So i am thinking to use zbmini to connect to one of sonoff 3 gang out line to power up zbmini. how ever it doesn’t work.

so need help here. sorry about the wording
might be a but confusing

:bulb: you just give me an idea.
i just use relay instead of zbmini.

it just a switch anway. the 3gang switch, when activated, turn on the relay which act as switch to the other phase circuit.

it can work isnt it?