Use /clone on a sticky piston and the block in front of it, placing the clone away from the original. place a block in front of the original piston and then place three blocks in front of the clone. Power the clone piston first and then when you power the original piston on and off it fuses the three block in front of the clone.
sidenote it could be a visual glitch because the light levels of the fused blocks are frozen.
the command I used in the command block was “clone ~~1~ ~-1~1~ ~~1~3”
cb
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We're tracking this issue in MCPE-111632, so this ticket is being resolved and linked as a duplicate.
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